JP2001244755A - High-frequency amplifier circuit and mobile phone terminal using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency amplifier circuit that can prevent deterioration in speech quality during low gain and suppress radiation of unwanted radio waves during low gain. SOLUTION: An amplifier 3, a filter 4, and changeover switches 2, 5 causing the amplifier 3 and a filter 4 to function selectively are provided between a signal input terminal 1 and a signal output terminal 6. A high-frequency signal given to the signal input terminal 1 is amplified by the amplifier 3, and the amplified signal is given to the signal output terminal 6 in a 1st mode with a high gain. Furthermore, the high-frequency signal given to the signal input terminal 1 is given to a filter 4, desired frequency components in the high-frequency signal is fed to the signal output terminal 6 to attenuate unwanted frequency components in a 2nd mode with a low gain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency amplifier circuit provided in a high-frequency circuit section of a receiving section of a mobile communication terminal such as a mobile phone terminal for amplifying a high-frequency signal and a mobile phone terminal using the same. It is. In particular, the present invention relates to a high-frequency amplifier circuit that performs gain control by a control voltage and a mobile phone terminal using the same.

[0002]

2. Description of the Related Art Recently, in the field of mobile communication, a CDMA (Code Division Multiple Access) system has become a global standard as a communication system. In such a communication system,
In order to ensure speech quality, it is necessary to prevent an increase in the bit error rate during speech communication, and it is essential to adjust gain according to the distance between the mobile phone terminal and the base station.

[0003] Hereinafter, a description will be given of a conventional typical portable telephone terminal compatible with the CDMA system, in which gain control is performed particularly in a receiving unit in a radio unit.

FIG. 9 is a block diagram showing a configuration of a radio section of a conventional typical portable telephone terminal. In FIG. 9, the wireless unit of the mobile phone terminal includes a transmitting unit 200 and a receiving unit 300
, A synthesizer section 400 and a duplexer section 500.

[0005] The receiving section 300 receives a received signal (about 850 MHz in the case of the IS-95 system) received by the duplexer section 500.
Variable gain high frequency amplifier circuit 30 for high frequency amplification of z)
1 and a band-pass filter 302 for extracting a reception frequency signal from an output signal of the variable gain high-frequency amplifier circuit 301
And a local oscillation signal (for example, 750 MHz) supplied from the synthesizer unit 400 to convert the reception frequency signal into an intermediate frequency modulated signal output (intermediate frequency modulated signal, for example, 110 MHz). It comprises a down converter 303 and a band pass filter 304 for extracting an intermediate frequency signal from an output signal of the down converter 303.

The transmitting section 200 mixes an intermediate frequency modulation signal input (intermediate frequency modulation signal) with a local oscillation signal supplied from the synthesizer section 400 to convert the intermediate frequency modulation signal into a transmission frequency. Converter 201, a variable-gain high-frequency amplifier 202 for amplifying the output signal of the up-converter 201 up to about 10 mW, and an output signal (10 mW
) To a maximum of about 1 W, and a high-output high-frequency amplifier circuit 203 with a fixed gain, and an isolator 204 that supplies the output of the high-output high-frequency amplifier circuit 203 to a duplexer unit 500 for transmitting as an electric wave.

The synthesizer section 400 includes a temperature controlled crystal oscillator (TCXO) 401 and a phase locked loop (P
LL) circuit 402 and a voltage controlled oscillator (VCO) 403.

[0008] The duplexer section 500 includes an antenna 501 and a duplexer 502.

FIG. 10 shows a receiving section 300 and a duplexer section 5 in the radio section of the CDMA portable telephone terminal shown in FIG.
A block diagram of a portion corresponding to 00 is shown. In FIG. 10, a duplexer 109 has a function of transmitting a reception signal received by an antenna 107 to a high-frequency amplification circuit 106 and transmitting a transmission signal input from a signal input terminal 108 to the antenna 107. Specifically, the duplexer 109 allows the signal to pass in the direction from the terminal 109c to the terminal 109b, and blocks the signal in the direction from the terminal 109b to the terminal 109c.
b → the terminal 109a is passed, the terminal 109a → the terminal 109b is blocked, and the terminal 109a → the terminal 109b is blocked.
It has a function of blocking the direction of c and blocking the direction from the terminal 109c to the terminal 109a.

The high-frequency amplifier circuit 106 has a built-in gain control function, and amplifies a signal of a reception frequency by about 15 dB at the maximum.

The band-pass filter 105 attenuates unnecessary signals at frequencies other than the intended reception frequency.

The down converter 103 receives a signal received from the high frequency amplifier circuit 106 and a local oscillation signal from the voltage controlled oscillator 104 at an RF terminal (high frequency signal terminal) and an LO terminal (local oscillation signal terminal), respectively. As a result, the reception frequency and the local oscillation frequency are mixed, so that the frequency of the reception signal is converted to an intermediate frequency, and the intermediate frequency reception signal is output from the IF terminal (intermediate frequency signal terminal).

Here, the frequency of the received signal input to the RF terminal of the down converter 103 is fc, and the voltage controlled oscillator 10 input to the LO terminal of the down converter 103 is
Assuming that the local oscillation frequency of F.4 is flo and the frequency of the intermediate frequency modulation signal output from the IF terminal of the down converter 103 is fif, the frequency of each signal has a relationship of fif = fc-fl. Output as fif. The intermediate frequency and the local oscillation frequency are as described above as examples.

Here, the operation of the CDMA portable telephone terminal will be described. The received signal input from the antenna 107 enters the duplexer 109 from the terminal 109b, is output from the terminal 109a, and is output from the terminal 109a.
After the unnecessary frequency components are attenuated by the band-pass filter 105 composed of, for example, a surface acoustic wave filter, the voltage-controlled oscillator 104 and the down-converter 103 convert the frequency into a reception signal of a predetermined intermediate frequency. .

The intermediate frequency reception signal that has entered the band pass filter 102 is sent to the signal output terminal 101 after frequency components other than the intermediate frequency reception signal are attenuated.

In the configuration shown in FIG. 10 described above, when the distance between the portable terminal and the base station is long and the signal strength of the received signal is weak, the high-frequency amplifier circuit 106 of the receiving unit supplies sufficient signal strength to the down converter 103. In order to input the received signal of
It needs to operate at high gain.

At this time, also in the transmission section, the high-output high-frequency amplifier circuit in the transmission section outputs a transmission signal having a strong signal strength in order to transmit a signal to a base station that is far away. A part of the transmission signal leaks from the terminal 109c of the duplexer 109 to the terminal 109a and is input to the high-frequency amplifier circuit 106 of the reception unit. However, since the transmission signal strength is strong, it interferes with the reception unit. Specifically, the leakage of the transmission signal to the receiving unit causes distortion of the received signal in the high-frequency amplifier circuit 106 of the receiving unit, which leads to deterioration of communication quality. In order to reduce the influence of the transmission signal, the high-frequency amplifier circuit 106 of the receiving section needs to operate with low distortion during high-gain operation.

In general, a high-frequency circuit is more likely to be distorted as the signal strength of an input signal is higher. The distance between the mobile terminal and the base station is short,
When the signal strength of the received signal is strong, the signal is amplified by the high frequency amplifier circuit 106, the signal strength of the received signal input to the down converter 103 becomes too strong, and the received signal may be distorted in the down converter 103. . In order to avoid the deterioration of the communication quality due to the occurrence of the distortion in the down converter 103, the high-frequency amplifier circuit 106 performs stepwise gain control of about two steps, and the signal input to the down converter 103 becomes too strong. I try not to.

Next, a specific configuration of the high-frequency amplifier circuit 106 having the gain control function shown in FIG. 10 will be described with reference to FIG. This high-frequency amplifier circuit 106
As shown in FIG. 11, a signal input terminal 601, a changeover switch 602, an amplifier 603, and a changeover switch 604
, A signal output terminal 605, a power supply terminal 606, and a control terminal 607.

More specifically, the common terminal 602a of the changeover switch 602 is connected to the signal input terminal 601, the changeover terminal 602b of the changeover switch 602 is connected to the changeover terminal 604b of the changeover switch 604, and the changeover terminal 602c of the changeover switch 602 is connected. The input terminal 603a of the amplifier 603 is connected to the output terminal 603b of the amplifier 603, the switch terminal 604c of the switch 604 is connected, and the signal output terminal 605 is connected to the common terminal 604a of the switch 604. The power terminal 606 is connected to the power terminal 603c of the amplifier 603, and the control terminal 607 is connected to the control terminals 602d and 604d of the switches 602 and 604.

The changeover switch 602 includes a common terminal 602a
Switching terminals 602b, 602
c has a function of selectively outputting to either one of them, and the switching is performed according to the level of the control voltage applied to the control terminal 602d.

The changeover switch 604 includes a changeover terminal 604
b, 604c has a function of selectively outputting one of the high-frequency signals to the common terminal 604a, and the switching is performed according to the level of the control voltage applied to the control terminal 604d.

When a predetermined power supply voltage is applied to the power supply terminal 606, the amplifier 603 amplifies the high-frequency signal input to the input terminal 603a by, for example, about 15 dB and outputs it from the output terminal 603b. Power terminal 606
Is opened or grounded, and the supply of the power supply voltage stops, the amplifier 603 stops the amplification operation and the power consumption is eliminated.

In the high-frequency amplifier circuit as described above, by switching the level of the control voltage applied to the control terminals 602d and 604d and switching the changeover switches 602 and 604, it is possible to perform a two-stage high-low gain control. Specifically, it is as shown below.

When the gain is high, the changeover terminal 602c is selected as the output of the changeover switch 602.
A control voltage is applied to each of the four inputs so that the switching terminal 604c is selected. At this time, a predetermined power supply voltage is applied to the power supply terminal 606. In such a state, the high-frequency signal input from the signal input terminal 601 is
The signal is amplified by the amplifier 603. The output signal of the amplifier 603 is sent to the signal output terminal 605 via the changeover switch 604.

When the gain is low, the switch terminal 602b is selected as the output of the switch 602,
So that the switching terminal 604b is selected as the input of
A control voltage is applied to each. At this time, the power terminal 6
06 is open or grounded. In such a state, the high-frequency signal input from the signal input terminal 601 is sent to the signal output terminal 605 via the changeover switch 602 and the changeover switch 604 without being amplified by the amplifier 603.

As described above, in the high-frequency amplifier circuit 106 having a built-in gain control function of FIG. 10, depending on the level of the control voltage, the high-frequency input signal is output after being amplified by the amplifier 603 or bypassing the amplifier 603. Gain control is performed by selecting whether to output as it is.

FIG. 12 is a graph showing the relationship between power amplification factor (gain) and frequency during high-gain operation and low-gain operation of the high-frequency amplifier circuit 106. X1 is at the time of high gain,
X2 is at the time of low gain.

The amplifier 603 for amplifying a high-frequency signal is usually designed so that the largest power amplification factor can be obtained at a desired frequency by using an input matching circuit and an output matching circuit. Is the amplifier 60
3 and output as it is, the power amplification factors of the desired frequency and other frequencies become almost the same.

FIG. 13A shows the relationship between the signal strength and the frequency of the input signal of the high-frequency amplifier circuit 106 shown in FIG. 10, and FIG. 13B shows the relationship between the RF signal and the LO terminal of the down converter 103. FIG. 13C shows the relationship between the signal strength and the frequency of the output signal output from the input terminal of the high-frequency amplifier circuit 106. FIG. In the figure, the solid line shows the characteristics when the input signal intensity is low and the high frequency amplifier circuit 106 operates at high gain, and the dotted line shows the input signal intensity when the high frequency amplifier circuit 1 is strong.
06 is the characteristic when the low gain operation is performed. However,
In FIG. 13, it is assumed that the bandpass filter 105 is not provided.

In the circuit shown in FIG. 10, when the desired frequency to be received is fc, the frequency of the local oscillation signal is flo, and the intermediate frequency is fif, the frequency is set such that fif = fc-fl. ing.

The input signal of the high-frequency amplifier 106 includes not only the desired frequency fc to be received but also fc−fif × (1 /
2), it is assumed that an interference wave signal having two frequencies of fc-2 × fif.

The signals of the desired frequency and the two interference waves are input to the RF terminal of the down converter 103,
When the local oscillation signal is input to the O terminal, the IF terminal of the down-converter 103 outputs an intermediate frequency signal, which has been frequency-converted by the desired frequency signal and the local oscillation signal, to fif, where fc−fif × (1 / 2), an interference wave signal having a frequency component of fc-2 × fif is also converted to fif.

For example, if the desired frequency fc is 850 MHz
When the local oscillation frequency flo is 740 MHz, the intermediate frequency is 110 MHz.

The frequency of fc−fif × (１ ／) is called a half IF, and is 795 MHz in this example.
It is. In the case of a half IF frequency, the second
The harmonic is mixed with the second harmonic of the local oscillation frequency flo to be converted to the intermediate frequency fif. That is, 2 × 7
95MHz-2 x 740MHz = 110MHz,
Intermediate frequency fif obtained by down-converting desired frequency fc
And the frequency becomes the interference signal.

The frequency of fc−2 × fif is called an image and is 630 MHz. In the case of an image, the frequency is converted to the intermediate frequency fif by mixing the frequency and the local oscillation frequency flo in the same manner as described above. That is, 740 MHz-630 MHz = 110 MHz, the same frequency as the intermediate frequency fif obtained by down-converting the desired frequency fc, and becomes an interference wave signal.

A local oscillation signal leaks to the RF terminal of the down-converter and is output. This signal leaks from the output terminal of the high-frequency amplifier circuit 104 to the input terminal of the high-frequency amplifier circuit 104 and is output.

FIG. 13A shows a desired frequency signal, an image signal, and a half IF signal, which are input to the high frequency amplifier circuit 106. As mentioned above,
The solid line shows the case where the input signal strength is weak, and the dotted line shows the case where the input signal strength is strong.

On the other hand, the strength of the desired frequency signal output from the output terminal of the high-frequency amplifier circuit 106 can be determined by comparing the solid line and the dotted line in FIG. Is strong (dotted line)
Is also at the same level as when the input signal strength is weak (solid line).

However, in the signal strength of the interference wave signal in the output signal of the high frequency amplification circuit 106 shown in FIG. 13B, the desired frequency signal and the interference signal are almost the same when the high frequency amplification circuit 106 operates at a low gain. Gain (-2 to -1d
B), the signal intensity of the interference signal input to the RF terminal of the down converter 103 cannot be reduced. Therefore, I of down converter 103
At the F terminal, the signal strength of the signal obtained by converting the interference signal into fif cannot be reduced.

That is, when the high frequency amplifying circuit 106 operates at a high gain, the desired frequency signal in the output signal of the high frequency amplifying circuit 106 is output by the filter function of the high frequency amplifying circuit 106 as shown by a solid line in FIGS. The level difference Zho between the desired frequency signal and the interference signal in the input signal of the high frequency amplifier circuit 106.
can be larger than hi.

However, when the high-frequency amplifier circuit 106 operates at a low gain, there is no filter function.
As shown by the dotted line in FIG. 7B, the level difference Zlo between the desired frequency signal and the interference signal in the output signal of the high frequency amplifier circuit 106 is equal to the level difference Zli between the desired frequency signal and the interference signal in the input signal of the high frequency amplifier circuit 106. I can only do the same.

When the high-frequency amplifier circuit 106 operates at a low gain, it has no filter function.
6 passes through the input terminal of the high-frequency amplifier circuit 106 as it is, the local oscillation signal output from the input terminal of the high-frequency amplifier circuit 106 during the high-gain operation as shown in FIG. Become larger.

After all, in the high-frequency amplifier circuit 106, when the received signal strength is high, the output level of the desired frequency in the output signal can be reduced by reducing the gain, but the interference wave cannot be suppressed. . In addition, the local oscillation signal leaking to the RF input terminal of the down converter 103 is output to the signal input terminal side with almost no suppression, and unnecessary radio waves may be emitted.

[0045]

In the case of a CDMA type portable telephone terminal, a signal of the same frequency is shared and used by a plurality of users at the same time. TDMA
A better distortion characteristic is required as compared with a (Time Division Multiple Access) type mobile phone terminal.

When the reception signal strength is low, the transmission signal strength is high, and this transmission signal is
This is because distortion is likely to occur in the high-frequency amplification circuit 106 of the reception unit due to the signal passing through the high-frequency amplification circuit 106 of the reception unit through the signal path. In order to suppress the occurrence of distortion when the transmission signal strength is high, a very low distortion amplifier is used as the high frequency amplifier circuit 106.

On the other hand, when the received signal strength is strong, the high-frequency amplifier circuit 106 performs stepwise gain control of about two steps in order to avoid a deterioration in speech quality due to the occurrence of distortion in the downconverter 103. So that the signal strength input to is not too strong.

However, the conventional high-frequency amplifier circuit 10
Specifically, as shown in FIG. 11, when the gain is high, the amplifier 6 passes through the amplifier 603 and when the gain is low, the amplifier 6 bypasses the amplifier 603. That is, at the time of high gain, the interference function of a frequency other than the desired frequency signal can be sufficiently attenuated by the filter function of the matching circuit or the like built in the amplifier 603, but at the time of low gain, there is no filter function as described above. Therefore, the interfering wave is directly input to the down converter 103, and the communication quality is degraded. Further, although the transmission signal has a weak signal strength, it passes through the high-frequency amplifier circuit 106 as it is and enters the down converter 103, which also deteriorates the communication quality.

Further, the local oscillation frequency signal leaks from the RF terminal of the down converter 103, passes through the high frequency amplifier circuit 106 as it is, is output to the duplexer 109 and the antenna 107, and may be radiated as unnecessary radio waves.

As the interference wave, in addition to the above-described image and the half IF, a third-order intermodulation distortion (IM
It is conceivable that 3) is generated. The third-order intermodulation distortion is proportional to the cube of the input power and increases in level. Since a distortion component at a frequency close to the intermediate frequency (110 MHz) has a great effect on speech quality, it is sufficiently suppressed. It is necessary.

For example, if the desired frequency fc is 850 MHz
When the local oscillation frequency flo is 740 MHz and the intermediate frequency fif is 110 MHz, a frequency fc '= 850.9 MH which is 0.9 MHz away from the desired frequency fc.
z, frequency fc ″ separated by 1.7 MHz = 852.5 MH
Consider a case where z is input as an interference wave. In this case, 3rd-order intermodulation distortion (IM3) of 2 × fc′−fc ″ = 850.1 MHz and 2 × fc ″ −fc ′ = 852.5 MHz occurs. When the signal passes through the down converter, the former frequency becomes 110.1 MHz, and the latter becomes 112.5 MHz. If the former level is high, the speech quality is adversely affected.

In order to avoid this problem, it is necessary to use a surface acoustic wave filter or the like which has a steep frequency characteristic and has a characteristic of greatly attenuating signals other than the desired received signal as the band-pass filter 105. Yes, such bandpass filters are generally expensive and bulky.

Accordingly, it is an object of the present invention to provide a high-frequency amplifier circuit capable of preventing a deterioration in speech quality at the time of low gain, and a portable telephone terminal using the same.

Another object of the present invention is to provide a high-frequency amplifier circuit capable of suppressing the emission of unnecessary radio waves at the time of low gain, and a portable telephone terminal using the same.

[0055]

SUMMARY OF THE INVENTION A high frequency amplifier circuit according to the present invention is provided between a signal input terminal and a signal output terminal, and between a signal input terminal and a signal output terminal, for transmitting a high frequency signal input to the signal input terminal. An amplifier for amplifying and supplying an output signal to a signal output terminal; and a desired frequency component of a high-frequency signal input to the signal input terminal provided between the signal input terminal and the signal output terminal is output to the signal output terminal. A filter that supplies as a signal and attenuates unnecessary frequency components;
In the first mode, a function selection circuit is provided for extracting an output signal from the amplifier from the signal output terminal in the first mode, and for extracting the output signal from the filter from the signal output terminal in the second mode, according to the control voltage.

According to this configuration, when the input signal strength is high, the gain of the signal in the desired frequency band is reduced. However, since the filter is operated at this time, the interference wave can be attenuated by the filter, and the portable telephone terminal In such a case, it is possible to sufficiently suppress the interfering wave entering the down-converter, and prevent deterioration of the communication quality at the time of low gain. Therefore, for example, when used in a mobile phone terminal, a high-precision band-pass filter provided on the input side of the down-converter is not required, and downsizing and price reduction can be achieved. Further, the local oscillation signal leaking from the down converter can be sufficiently attenuated by the filter, and the emission of unnecessary radio waves to the outside can be sufficiently reduced.

In the above configuration, in the first mode, a predetermined power supply voltage is supplied to the amplifier, and in the second mode, the supply of the power supply voltage to the amplifier is stopped or cut off so that no operating current flows to the amplifier. Is also good.

According to this configuration, the input signal strength is strong,
When it is necessary to reduce the gain, the gain can be reduced and the current consumption of the amplifier can be reduced to almost zero by setting the second mode. For example, when used in a mobile phone terminal, the standby time of the mobile phone terminal can be lengthened.

In the above configuration, the control voltage may be high in the first mode, low in the second mode, and the control voltage may be supplied to the amplifier as a power supply voltage.

According to this configuration, the power supply for the amplifier and the power supply for controlling the gain are not separately required, and the circuit configuration can be simplified. For example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

The above filter is composed of, for example, a capacitor and an inductor.

According to this configuration, since the element constituting the filter can be formed on a semiconductor chip or by a small chip component, the above function can be realized with a smaller size. For example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

When the filter is selectively operated in the second mode, it is possible to use the parasitic capacitance of the amplifier whose operation has been stopped as one of the capacitors of the filter.

According to this configuration, since the amplifier is used as an element constituting a filter, the above function can be realized with a smaller size. For example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

On the other hand, the function selection circuit connects, for example, a common terminal to a signal input terminal, connects one switching terminal to an input terminal of an amplifier, connects the other switching terminal to an input terminal of a filter, and connects a control voltage to a control voltage. A first switch that is switched in response to the first switch, an output terminal of the amplifier connected to one of the switching terminals, an output terminal of the filter connected to the other switching terminal,
A second switch that switches according to the control voltage, wherein the second switch switches to one switch terminal when the first switch switches to one switch terminal. When the first switch is switched to the other switch terminal, the second switch is switched to the other switch terminal.

According to this configuration, the function selection circuit can be realized with a simple configuration including only the first and second changeover switches. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

The function selection circuit has another configuration in which one terminal is connected to the signal input terminal, the other terminal is connected to the input terminal of the filter, and conduction is performed according to the control voltage.
A switch for opening and a switch for connecting one switching terminal to the output terminal of the amplifier, connecting the other switching terminal to the output terminal of the filter, and performing switching in accordance with a control voltage; When the switch is opened, the changeover switch is switched to the one changeover terminal side, and when the switch is turned on, the changeover switch is changed over to the other changeover terminal side.

According to this configuration, the function selection circuit can be realized with a simple configuration including only switches and changeover switches. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

The above-mentioned changeover switch may be constituted by first and second unit switches which have one terminal connected in common and which conducts and opens oppositely to each other.

The filter includes, for example, an inductor in which one terminal is connected to the input terminal and the other terminal is grounded at a high frequency, and one terminal is connected to the input terminal and the other terminal is connected to the output terminal. And a capacitor.

According to this configuration, since the element constituting the filter can be formed on a semiconductor chip or by a small chip component, the above function can be realized with a smaller size. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

The filter includes, for example, an inductor in which one terminal is connected to the input terminal and the other terminal is connected to the output terminal, and one terminal is connected to the other terminal of the inductor and the other terminal is connected to the high frequency. And a grounded capacitor.

According to this configuration, since the element constituting the filter can be formed on a semiconductor chip or with a small chip component, the above function can be realized with a smaller size. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

The filter includes, for example, a first inductor having one terminal connected to the input terminal, one terminal connected to the other terminal of the first inductor, and the other terminal grounded at a high frequency. A first capacitor, a second inductor having one terminal connected to the other terminal of the first inductor and the other terminal grounded at a high frequency,
And a second capacitor having one terminal connected to the other terminal of the inductor and the other terminal connected to the output terminal.

According to this configuration, the element constituting the filter can be formed on a semiconductor chip or by a small chip component, so that the above function can be realized with a smaller size. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

The amplifier includes, for example, at least one field-effect transistor and an input matching circuit provided between a signal input terminal and a gate terminal of the field-effect transistor. One terminal is connected to the gate, the other terminal is connected to the input terminal of the filter, a switch that conducts and opens according to the control voltage, and one switching terminal is connected to the output terminal of the amplifier, and the output terminal of the filter is connected. And a switching switch for performing switching in accordance with a control voltage. In the second mode, the input matching circuit and the parasitic capacitance of the field-effect transistor whose operation is stopped are configured as a filter. Used as an element.

According to this configuration, since the input matching circuit and the parasitic capacitance of the field-effect transistor whose operation is stopped are used as components of the filter, the components constituting the filter can be shared with the components of the amplifier. Can be reduced. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

The above input matching circuit comprises an inductor having one end connected to the signal input terminal and the other end connected to the gate terminal of the field effect transistor.

The first and second unit switches are as follows:
For example, a field-effect transistor having a field-effect transistor in which one of a drain terminal and a source terminal is connected to one terminal and the other of the source terminal and the drain terminal is connected to the other terminal, and constitutes a first unit switch The control voltage is applied to the source terminal, the reference voltage is applied to the gate terminal, and the control voltage is applied to the gate terminal and the reference voltage is applied to the source terminal of the field effect transistor forming the second unit switch. Is something that can be done.

According to this configuration, the first and second modes can be switched by one control voltage, and the mode switching control can be easily performed.

The changeover switch comprises, for example, first and second unit switches for connecting one terminal in common and conducting and opening oppositely to each other. The first and second unit switches are, for example, each having one terminal. And a field-effect transistor in which one of a drain terminal and a source terminal is connected to the other terminal and the other of the source terminal and the drain terminal is connected to the other terminal. A control voltage is applied to the terminal, a reference voltage is applied to the gate terminal, and a control voltage is applied to the gate terminal and a reference voltage is applied to the source terminal of the field-effect transistor constituting the second unit switch. For example, one of the terminals is connected to one of the drain terminal and the source terminal, and the other terminal is connected to the source terminal. Has a field-effect transistor and the other of which is connected to the drain terminal, the field effect transistors constituting the switch, with a control voltage is applied to the gate terminal, a reference voltage is applied to the source terminal.

According to this configuration, the first and second modes can be switched by one control voltage, and the mode switching control can be easily performed.

The portable telephone terminal of the present invention has a built-in high-frequency amplifier circuit for amplifying a received signal at a high frequency. An amplifier provided to amplify a reception signal input to the signal input terminal and to supply the output signal to the signal output terminal; and a receiver provided between the signal input terminal and the signal output terminal and input to the signal input terminal. A filter for supplying a desired frequency component of the signal to the signal output terminal as an output signal and attenuating an unnecessary frequency component; extracting a signal output from the amplifier from the signal output terminal in the first mode; In the mode, an output signal from the filter is extracted from a signal output terminal.

According to this configuration, when the input signal strength is high, the gain of the signal in the desired frequency band is reduced. However, since the filter is operated at this time, the interfering wave can be attenuated by the filter, and the signal is transmitted to the down converter. Incoming interfering waves can be sufficiently suppressed, and deterioration of speech quality at low gain can be prevented. Therefore, a high-precision bandpass filter is not required as the bandpass filter provided on the input side of the downconverter, and a reduction in size and cost can be achieved. Further, the local oscillation signal leaking from the down converter can be sufficiently attenuated by the filter, and the emission of unnecessary radio waves to the outside can be sufficiently reduced.

[0085]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a high-frequency amplifier circuit according to an embodiment of the present invention and a portable telephone terminal using the same will be described.
This will be described with reference to the drawings.

[First Embodiment] FIG. 1 is a block diagram showing a configuration of a high-frequency amplifier circuit according to a first embodiment of the present invention. The high-frequency amplifier circuit of FIG. 1 corresponds to the high-frequency amplifier circuit 106 having a built-in gain control function in the block diagram of the receiving section of the conventional mobile phone terminal shown in FIG. That is, in the mobile phone terminal of the embodiment of the present invention, the high-frequency amplifier circuit of FIG. 1 is used in place of the high-frequency amplifier circuit 106 in the receiving section of the conventional mobile phone terminal shown in FIG.

Hereinafter, the high-frequency amplifier circuit of FIG. 1 will be described in detail.

As shown in FIG. 1, this high-frequency amplifier circuit includes a signal input terminal 1, a changeover switch 2 having a mode switching function, an amplifier 3, a filter 4, a changeover switch 5 having a mode switching function, Signal output terminal 6 and GN
It comprises a D terminal 7, a power (Vdd) terminal 8, a control terminal 9, and a reference (Vref) terminal 11.

Specifically, the common terminal 2a of the changeover switch 2 is connected to the signal input terminal 1, the input terminal 3a of the amplifier 3 is connected to the changeover terminal 2b of the changeover switch 2, and the output terminal 3b of the amplifier 3 is changed over. The switching terminal 5 b of the switch 5 is connected, the input terminal 4 a of the filter 4 is connected to the switching terminal 2 c of the switching switch 2, the switching terminal 5 c of the switching switch 5 is connected to the output terminal 4 b of the filter 4, The signal output terminal 6 is connected to the common terminal 5a.

The amplifier 3 is connected to the GND terminal 7 which is grounded.
Is connected to the power terminal 8 to which the power voltage Vdd is applied, and the power supply terminal 3c of the amplifier 3 is connected to the control terminal 9 to which the control voltage Vc is applied.
Are connected to the reference terminals 11 to which the reference voltage Vref is applied. The reference terminals 2e and 5e of the changeover switches 2 and 5 are connected to the reference terminal 11 to which the reference voltage Vref is applied.

The changeover switch 2 has a function of selectively outputting a high-frequency signal input from the common terminal 2a to one of the changeover terminals 2b and 2c. The changeover is performed by a control voltage applied to the control terminal 2d. And the level of the reference voltage applied to the reference terminal 2e.

The changeover switch 5 has a function of selectively outputting one of the high-frequency signals input from the changeover terminals 5b and 5c to the common terminal 5a. The changeover is performed by controlling the control voltage applied to the control terminal 5d. And the level of the reference voltage applied to the reference terminal 5e.

When a predetermined power supply voltage is applied to the power supply terminal 8, the amplifier 3 amplifies the high-frequency signal input to the input terminal 3a by, for example, about 15 dB and outputs it from the output terminal 3b. In this case, the amplifier 3 has a filter characteristic of passing a desired frequency component and attenuating a frequency component other than the desired frequency.
The signal is amplified by about 5 dB, but the frequency components other than the desired frequency are amplified at a lower amplification factor. When the power supply terminal 8 is opened or grounded and the supply of the power supply voltage is stopped, the amplifier 3 stops the amplification operation,
Its power consumption is gone.

The filter 4 allows the desired frequency component of the high-frequency signal input to the input terminal 4a to pass therethrough, attenuates frequency components other than the desired frequency, and outputs the signal from the output terminal 4b. In this case, in the filter 4, the gain of the desired frequency component decreases by, for example, about -1 to -2 dB.

In the high-frequency amplifier circuit as described above, the level of the control voltage applied to the control terminals 2d and 5d is switched, and the switches 2 and 5 are switched.
It is possible to perform gain control in two steps, high and low. Specifically, it is as shown below.

At the time of high gain, a control voltage is applied to each of the changeover switch 2 such that the changeover terminal 2b is selected as the output of the changeover switch 2 and the changeover terminal 5b is selected as the input of the changeover switch 5. At this time, a predetermined power supply voltage is applied to the power supply terminal 8. In such a state, the high-frequency signal input from the signal input terminal 1 is amplified by the amplifier 3. The output signal of the amplifier 3 is sent to the signal output terminal 6 via the changeover switch 5. In this case, the desired frequency component of the high frequency signal input from the signal input terminal 1 is amplified by about 15 dB and sent to the signal output terminal 6, and the frequency components other than the desired frequency are amplified at a lower amplification factor. Is sent to the signal output terminal 6.

When the gain is low, a control voltage is applied to each of the changeover switch 2 so that the changeover terminal 2c is selected as the output and the changeover terminal 5c is selected as the input of the changeover switch 5. At this time, the power supply terminal 8 is opened or grounded. In such a state, the high-frequency signal input from the signal input terminal 1 is not amplified by the amplifier 3,
Enter filter 4. The output signal of the filter 4 is sent to a signal output terminal 6 via a changeover switch 5. In this case, the desired frequency component of the high-frequency signal input from the signal input terminal 1 is attenuated by about -1 to -2 dB and the signal output terminal 6
The frequency components other than the desired frequency are sufficiently attenuated and sent to the signal output terminal 6.

As described above, in the high-frequency amplifier circuit having the gain control function shown in FIG. 1, depending on the level of the control voltage, the high-frequency input signal is amplified and output by the amplifier 3, or the input signal is bypassed by the amplifier 3 and filtered. By selecting whether to output the signal through 4, gain control is performed, and in both cases, frequency components other than the desired frequency are attenuated.

Here, as the amplifier 3, for example, a field effect transistor (hereinafter referred to as FET) is used.
The input terminal 3b, the power supply terminal 3c, and the ground terminal 3d of the amplifier 3 are connected to a gate electrode, a drain electrode,
Corresponds to the source electrode. The amplification of the signal of the FET as the amplifier 3 is performed by inputting a voltage signal to the gate terminal of the FET,
This is realized by extracting an operating current flowing between the source and the drain as an output signal. Control of the operating current of the FET is realized by a change in the potential between the gate and the source and a change in the potential between the drain and the source. As the amplifier 3, for example, a bipolar transistor may be used. It can be considered that the gate, drain, and source electrodes in the above description are replaced with base, collector, and emitter electrodes, respectively. A specific example of the amplifier 3 using the FET will be described later with reference to FIG.

Here, as the filter 4, for example, an LC filter using an inductor and a capacitor is used, and in a system using a high-frequency circuit, an unnecessary signal is attenuated as compared with a signal of a desired frequency and passed therethrough. Designed.

In the following description, the amplifier 3 is an FET
think of. Then, the power supply voltage V applied to the power supply terminal 8
dd is changed in conjunction with the control voltage Vc. Control voltage V
When c is controlled to the first voltage and the first and second changeover switches 2 and 5 are switched to the one of the switching terminals 2b and 5b, the power supply voltage Vdd is set so that the operating current flows through the amplifier 3. Is done. When the control voltage Vc is controlled to the second voltage and the first and second switches 2 and 5 are switched to the other switching terminals 2c and 5c, the amplifier 3
Is set to a power supply voltage Vdd such that signal amplification is not performed and an operating current does not flow through the amplifier 3 (for example, the power supply is stopped by setting the ground potential applied to the ground terminal to 0 V) or separated from the power supply voltage Vdd ( Cut off).

Next, the operation of the circuit shown in FIG. 1 will be briefly described. By setting the relationship between the control voltage Vc and the reference voltage Vref to a predetermined state, the first and second changeover switches 2 and 5 are switched to one of the switching terminals 2b and 5b, and a predetermined power supply voltage is applied to the power supply terminal 8. When Vdd is applied, the high-frequency signal input to the signal input terminal 1
After passing through the changeover switch 2, the signal is amplified by the amplifier 3, and then passes through the second changeover switch 5, and is output from the signal output terminal 6 as an amplified high-frequency signal.

On the other hand, the first and second changeover switches 2 and
5 to the other switching terminals 2c and 5c, and the amplifier 3
When the supply of power to the power supply is stopped or cut off, the high-frequency signal input to the signal input terminal 1 passes through the first changeover switch 2 and is input to the filter 4 without passing through the amplifier 3, and unnecessary frequency components are removed. After being attenuated, the signal passes through the second changeover switch 5 and is output from the signal output terminal 6 as a high-frequency signal. At this time, since the high-frequency signal does not pass through the amplifier 3, it is output as a signal attenuated by the loss of the first and second changeover switches 2, 5 and the filter 4.

At this time, since the input signal is output to the signal output terminal 6 through the filter 4, when a signal having an unnecessary frequency component is input to the signal input terminal 1 or the signal output terminal 6, the signal output is performed. The signal is output to the terminal 6 or the signal input terminal 1 after being attenuated more than the desired frequency.

FIG. 2 shows a specific circuit configuration of the first and second changeover switches 2 and 5 of FIG. In this example, the first and second changeover switches 2 and 5 have the same circuit configuration. In FIG. 2, one end of a capacitor 25 is connected to one switching terminal 22 (corresponding to the switching terminals 2b and 5b). The other end of the capacitor 25 has a resistor 2
9 and the source terminal of the field effect transistor 26 are connected. A resistor 27 is connected between the source terminal and the drain terminal of the field effect transistor 26. One end of a resistor 30 is connected to the gate terminal of the field effect transistor 26. One end of a capacitor 28 is connected to the drain terminal of the field effect transistor 26. The other end of the capacitor 28 has a common terminal 21
(Corresponding to the common terminals 2a and 5a) are connected.

The other switching terminal 23 (switching terminals 2c, 5c)
Is connected to one end of the capacitor 34. The other end of the capacitor 34 is connected to one end of the resistor 35 and the source terminal of the field effect transistor 32. A resistor 33 is connected between the source terminal and the drain terminal of the field effect transistor 32. One end of a resistor 36 is connected to the gate terminal of the field effect transistor 32. One end of a capacitor 31 is connected to the drain terminal of the field-effect transistor 32.
The other end of the capacitor 31 is connected to the common terminal 21.

The other end of the resistor 29 and the other end of the resistor 36 are connected to the reference terminal 39 (corresponding to the reference terminals 2e and 5e). Control terminal 40 (control terminal 2d,
5d), the other end of the resistor 30 and the resistor 35
Are connected to each other.

The field effect transistors 26 and 32
The positions of the source terminal and the drain terminal may be reversed.

The circuit shown in FIG. 2 can be considered as two switches each having one of the input terminals (one terminal) or the output terminal (the other terminal) connected to the common terminal 21.

The operation of the high-frequency amplifier circuit according to this embodiment having the above-described configuration will be described below.

The first and second changeover switches 2 and 5 in FIG. 2 will be described. The switching operation is performed based on the voltage values of the reference terminal 39 and the control terminal 40. As described above, the common terminal 2a of the first changeover switch 2 in FIG.
The one switching terminal 2b and the other switching terminal 2c correspond to the common terminal 21, one switching terminal 22, and the other switching terminal 23 in FIG. 2, respectively. Also, the common terminal 5a, one switching terminal 5b, and the other switching terminal 5c of the second switch 5 in FIG. 1 correspond to the common terminal 21, one switching terminal 22, and the other switching terminal 23 in FIG. 2, respectively. ing. Further, the reference terminal 5 of the first and second changeover switches 5 and 9 in FIG.
d and 9d correspond to the reference terminal 39 in FIG. 2, and the control terminals 5e and 9e of the first and second changeover switches 5 and 9 correspond to the control terminal 40 in FIG.

When the switching operation is performed in the circuit configuration of FIG. 2, the voltage applied to the control terminal 40 and the reference terminal 39 and the conduction / opening between the common terminal 21 and the one switching terminal 22 and the other switching terminal 23 are controlled. Is as follows.

Vc <Vref− | Vp |: Open between the common terminal 21 and the switching terminal 22 Vc> Vref: Conduction between the common terminal 21 and the switching terminal 22 Vc <Vref: Conduction between the common terminal 21 and the switching terminal 23 Vc> Vref + | Vp |: Open between the common terminal 21 and the switching terminal 23 where Vp is the threshold voltage of the field effect transistor 26.

When the control voltage Vc is in a relation of Vref− | Vp | ≦ Vc ≦ Vref with respect to the reference voltage Vref, the state between the common terminal 21 and the switching terminal 22 becomes an intermediate state between conduction and opening. I have. When the relationship of Vref ≦ Vc ≦ Vref + | Vp | is established, the state between the common terminal 21 and the switching terminal 23 is intermediate between conduction and opening.

In FIG. 2, the source terminal and the drain terminal of the field effect transistor 26 and the field effect transistor 32 are connected by a resistor 27 and a resistor 33, respectively, and have substantially the same potential. 29 and a resistor 35 connected to the source terminal of the field effect transistor 32, respectively.
May be connected to the drain terminals of the field effect transistor 26 and the field effect transistor 32. Thereby, the degree of freedom in circuit layout is improved.

Next, the gain control of the high-frequency amplifier circuit in the circuit of FIG. 1 will be described. As an example, it is assumed that the power supply voltage Vdd applied to the power supply terminal 8 is set to 3 V, the control voltage Vc applied to the control terminal 9 is set to 3 V, and the reference voltage Vref applied to the reference terminal 11 is set to 1.5 V. Also, the threshold voltage Vp of the field effect transistors 26 and 32 is -0.6 V
And

At this time, a control voltage Vc of 3 V is supplied from the control terminal 9 to the control terminal 2 d of the first switch 2 and the control terminal 5 d of the second switch 5. The reference terminal 2e and the reference terminal 5e of the second changeover switch 5 are 1.5
A reference voltage Vref of V is supplied. At this time, Vc> V
The relationship of ref is established, and conduction is conducted between the common terminal 2a and the switching terminal 2b of the first switch and between the common terminal 5a and the switching terminal 5b of the second switch 5. Also, V
The relationship of c> Vref + | Vp | is established, and the opening between the common terminal 2a and the switching terminal 2c of the first switch and the opening between the common terminal 5a and the switching terminal 5c of the second switch are opened.

In this state, a signal input to the high-frequency amplifier circuit is supplied from the signal input terminal 1 to the first switch 2.
Pass between the common terminal 2a and the switching terminal 2b, are input to the amplifier 3, are amplified by the amplifier 3, and sequentially pass between the switching terminal 5b and the common terminal 5a of the second changeover switch 5 to generate a signal output terminal. 6 is output.

Here, the gain of the amplifier 3 is G, the common terminal 2a and the switching terminal 2b of the first switch 2, the common terminal 2a and the switching terminal 2c, the common terminal 5a of the second switch 5 and the switching Between terminals 5b, common terminal 5a-switching terminal 5c
Let L be the signal loss between them.

In this case, the gain P of the high-frequency amplifier of FIG.
G1 is expressed by the following equation.

PG1 = G−2 × L (1) Next, the power supply voltage Vdd applied to the power supply terminal 8 is set to 0V, the control voltage applied to the control terminal 9 is set to 0V, and the reference terminal 11 is set.
Is set to 1.5V.

At this time, a control voltage Vc of 0 V is supplied from the control terminal 9 to the control terminal 2 d of the first changeover switch 2 and the control terminal 5 d of the second changeover switch 5. The reference terminal 2e and the reference terminal 5e of the second changeover switch 5 are 1.5
A reference voltage Vref of V is supplied. At this time, Vc <V
The relationship of ref is established, and conduction is established between the common terminal 2a and the switching terminal 2c of the first switch and between the common terminal 5a and the switching terminal 5c of the second switch 5. Also, V
The relationship of c <Vref- | Vp | is established, and the space between the common terminal 2a and the switching terminal 2b of the first switch and the space between the common terminal 5a and the switching terminal 5b of the second switch are opened.

In this state, the signal input to the high-frequency amplifier circuit is transmitted between the common terminal 2a and the switching terminal 2c of the first switch 2, the filter 4, and the switching terminal 5c of the second switch 5. Sequentially passing between the common terminals 5a,
The signal is output from the signal output terminal 6.

Here, assuming that the passing loss of the filter is L2, in this case, the gain PG2 of the high-frequency amplifier circuit of FIG.

PG 2 = −2 × L−L 2 (2) The high-frequency amplifier circuit of FIG. 1 switches the control voltage Vc applied to the control terminal 9 to make it clear from the equations (1) and (2). Thus, the gain can be changed by G + L2.

Further, the control voltage V applied to the control terminal 13
The operating current of the amplifier 3 can be reduced to zero by setting or cutting off the power supply voltage Vdd applied to the power supply terminal 8 of the amplifier 3 to 0 V in conjunction with setting c to 0V.

That is, the control voltage Vc applied to the control terminal 8
And the application of the power supply voltage Vdd to the power supply terminal 8 of the amplifier 3, the operating current when the gain is attenuated can be reduced. As described above, when the first and second changeover switches 2 and 5 are switched to the side bypassing the amplifier 3 when the control voltage Vc is 0 V, the control terminal 9 and the power supply terminal 8 are connected to each other. May be connected in common, in which case the number of terminals can be reduced.

The reference voltage applied to the source terminal of the first field-effect transistor 26 is increased by a value corresponding to the threshold voltages of the first and second field-effect transistors 26 and 32 to the second field-effect transistor 32. Can be set higher than the reference voltage applied to the gate terminal.

For example, if the threshold voltage is -0.6 V
, The reference voltage Vref1 applied to the source terminal of the first field effect transistor 26 is set to 1.8 V,
Assuming that the reference voltage Vref2 applied to the gate terminal of the field effect transistor 32 is 1.2 V, the voltage range in which the first and second field effect transistors 26 and 32 are in an intermediate state between ON and OFF can be overlapped. That is, the first
The voltage at which the ON of the field effect transistor 26 is determined and the voltage at which the OFF of the second field effect transistor 32 is determined can be the same voltage. The voltage at which ON of the second field-effect transistor 32 is determined can be the same voltage.

The control voltage needs to be set so as to avoid a voltage range where the first and second field-effect transistors 26 and 32 are in an intermediate state between on and off. Second field effect transistor 2
The first and second field-effect transistors 26 and 32 are compared with the case where the reference voltage applied to
The setting range of the control voltage for turning on and off the power supply can be widened.

As described above, when the same reference voltage is used, when the reference voltage is 1.5 V, the upper value of the control voltage Vc needs to be set to a value exceeding 2.1 V. Was required to be set to a value of less than 0.9 V, but as described above, one of the reference voltages was 1.8 V,
Assuming that the other voltage is 1.2 V, the upper value of the control voltage Vc may be a value exceeding 1.8 V, and the lower value of the control voltage Vc may be set to a value less than 1.2 V.

FIG. 3 shows an example of a first specific circuit configuration (high-pass filter) of the filter 4 in FIG. Input terminal 41 (connected to switching terminal 2c in FIG. 1)
Is connected to one end of an inductor 44 and one end of a capacitor 45. GND on the other end of the inductor 44
Terminal 43 is connected. The GND terminal 43 is grounded. The other end of the capacitor 45 is connected to the output terminal 42 (connected to the switching terminal 5c in FIG. 1).

In the filter 4 configured as described above, a signal having a frequency lower than the frequency set by the values of the inductor 44 and the capacitor 45 is attenuated and passes.

When the filter is configured as described above,
When the capacitance value of the capacitor 31 or the capacitor 34 in FIG. 2 of the changeover switch 5 in FIG. 1 is set such that the combined capacitance value of the capacitor 31 and the capacitor 34 or both of them corresponds to the capacitance value of the capacitor 45, Alternatively, the capacitor 34 or both of them can be substituted for the capacitor 45. With this configuration, the capacitor 45 becomes unnecessary,
The number of components constituting the circuit can be reduced.

FIG. 4 shows an example of a second specific circuit configuration (low-pass filter) of the filter 4 in FIG. Input terminal 51 (connected to switching terminal 2c in FIG. 1)
Is connected to one end of an inductor 55. The other end of the inductor 55 is connected to one end of the capacitor 54 and the output terminal 52 (connected to the switching terminal 5c in FIG. 1). The other end of the capacitor 55 has a GND terminal 53
Is connected. The GND terminal 53 is grounded.

In the filter configured as described above, a signal having a frequency higher than the frequency set by the values of the capacitor 54 and the inductor 55 is attenuated and passes.

FIG. 5 shows an example of a third specific circuit configuration (bandpass filter) of the filter 4 in FIG.
One end of an inductor 65 is connected to the input terminal 61 (connected to the switching terminal 2c in FIG. 1). The other end of the inductor 65 is connected to one end of a capacitor 66, one end of an inductor 67, and one end of a capacitor 68. The other end of the capacitor 66 is connected to a GND terminal 63. GND terminals 63 and 64 are grounded.
The other end of the inductor 67 is connected to a GND terminal 64. The other end of the capacitor 68 is connected to an output terminal 62 (connected to the switching terminal 5c in FIG. 1).

In the filter configured as described above, signals having frequencies lower than and higher than the frequencies set by the values of the inductor 65, the capacitor 66, the inductor 67, and the capacitor 68 are attenuated and pass.

When the filter is configured as described above,
When the capacitance value of the capacitor 31 or the capacitor 34 is set such that the combined capacitance value of the capacitor 31 and the capacitor 34 or both of the changeover switch 5 in FIG. Alternatively, the capacitor 34 or both of them can be substituted for the capacitor 68. With this configuration, the capacitor 68 becomes unnecessary,
The number of components constituting the circuit can be reduced.

FIG. 6 shows an example of a specific circuit configuration of the amplifier 3 in FIG. One end of an inductor 75 is connected to the input terminal 71 (connected to the switching terminal 2b in FIG. 1). The other end of the inductor 75 is connected to the gate terminal of the FET 79. The source terminal of the FET 79 is connected to the GND terminal 74. GND terminal 74
Is grounded. One end of an inductor 76 and one end of a capacitor 78 are connected to a drain terminal of the FET 79. A power supply terminal 73 (FIG. 1)
And one end of a capacitor 77 are connected. The other end of the capacitor 77 is a GND terminal 80
Is connected. The GND terminal 80 is grounded. The other end of the capacitor 78 is connected to the output terminal 72 (connected to the switching terminal 5b in FIG. 1).

In the amplifier 3 configured as described above, the power supply voltage is applied to the amplifying FET via the inductor 76. The input matching circuit is composed of an inductor 75, and the output matching circuit is composed of an inductor 76 and a capacitor 78 grounded at high frequency via a capacitor 77.
Therefore, it is constituted.

When the amplifier 3 is configured as described above,
When the capacitance value of the capacitor 25 or the capacitor 28 is set such that the combined capacitance value of the capacitor 25 or the capacitor 28 or both of the changeover switch 5 of FIG. Alternatively, the capacitor 34 or both of them can be substituted for the capacitor 78. With this configuration, the capacitor 78 becomes unnecessary,
The number of components constituting the circuit can be reduced.

According to this embodiment, since the amplifier 3 and the filter 4 are selectively operated, when the input signal strength is strong, the gain of the signal in the desired frequency band is reduced. At this time, the filter 3 is operated. Therefore, the interference wave can be attenuated by the filter 4, and when used in a mobile phone terminal, the interference wave entering the down converter can be sufficiently suppressed, and the deterioration of the communication quality at low gain can be prevented. Can be. Therefore, for example, when used in a mobile phone terminal, a high-precision band-pass filter provided on the input side of the down-converter is not required, and downsizing and price reduction can be achieved. Further, the local oscillation signal leaking from the down converter can be sufficiently attenuated by the filter, and the emission of unnecessary radio waves to the outside can be sufficiently reduced.

In the first mode, a predetermined power supply voltage is supplied to the amplifier 3, and in the second mode, the supply of the power supply voltage to the amplifier 3 is stopped or cut off so that no operating current flows to the amplifier 3. Then, when the input signal strength is strong and the gain needs to be reduced, the gain can be reduced and the current consumption of the amplifier 3 can be reduced to almost 0 by setting the second mode. For example, when used in a mobile phone terminal, the standby time of the mobile phone terminal can be lengthened.

Further, if the control voltage is set to a high voltage in the first mode, the control voltage is set to a low voltage in the second mode, and the control voltage is supplied to the amplifier 3 as a power supply voltage, the control of the power supply and the gain of the amplifier 3 Does not require a separate power supply, thereby simplifying the circuit configuration. For example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

[Second Embodiment] FIG. 7 is a block diagram showing a configuration of a high-frequency amplifier circuit according to a second embodiment of the present invention. The difference from the high frequency amplifier circuit of FIG.
Instead of the changeover switch 2, a switch 82 for simply conducting / opening is used, one terminal 82 a of the switch 82 is connected to the signal input terminal 1, and the other terminal 82 of the switch 82 is connected.
c, the input terminal 4a of the filter 4 is connected, and the input terminal 3a of the amplifier 3 is directly (always) connected to the signal input terminal 1. Accordingly, the control terminal 82d of the switch 82 is connected to the control voltage input terminal 9, and the reference terminal 1
1 is connected to the reference terminal 82e of the switch 82.

Next, the operation of the circuit shown in FIG. 7 will be briefly described. Instead of switching the changeover switch 2 in FIG. 1 to the changeover terminal 2b side, a path from one terminal 82a of the switch 82 to the other terminal 82c is opened (cut off).
Then, instead of switching the changeover switch 2 in FIG. 1 to the changeover terminal 2c side, a path from one terminal 82a of the switch 82 to the other terminal 82c is made conductive.

By setting the relationship between the control voltage Vc and the reference voltage Vref to a predetermined state, the switch 82 is opened, the changeover switch 5 is switched to one of the switching terminals 5b, and a predetermined power supply voltage Vdd is applied to the power supply terminal 8. Then, the high-frequency signal input to the signal input terminal 1 is amplified by the amplifier 3, passes through the changeover switch 5, and is output from the signal output terminal 6 as an amplified high-frequency signal.

On the other hand, when the switch 82 is turned on, the changeover switch 5 is switched to the other switch terminal 5c, and the supply of power to the amplifier 3 is stopped or cut off, the high-frequency signal input to the signal input terminal 1 becomes After passing through the switch 82 and not passing through the amplifier 3, the signal is input to the filter 4, and unnecessary frequency components are attenuated. At this time, since the high-frequency signal does not pass through the amplifier 3, it is output as a signal attenuated by the loss of the switch 82, the changeover switch 5, and the filter 4.

At this time, since the input signal is output to the signal output terminal 6 via the filter 4, when a signal having an unnecessary frequency component is input to the signal input terminal 1 or the signal output terminal 6, The signal is output to the signal output terminal 6 or the signal input terminal 1 after being attenuated more than the desired frequency.

FIG. 8 shows a specific circuit configuration of the switch 82 of FIG. This switch does not include one of the switching terminals 22, the capacitor 25, the resistor 29, the field effect transistor 26, the resistor 27, the resistor 30, and the capacitor 28 in FIG. 2, and a terminal corresponding to the common terminal 21 in FIG. The terminal corresponding to the terminal 91 and the second switching terminal 23 in FIG.

In the field effect transistor 32, the positions of the source terminal and the drain terminal may be reversed.

The operation of the high-frequency amplifier circuit of the present embodiment configured as described above is similar to that of FIG.
The operation is the same as that of the high-frequency amplifier circuit of the first embodiment, except that the operation is the same as the operation between the common terminal 21 and the switching terminal 23 of the changeover switch.

Next, gain control of the high-frequency amplifier circuit in the circuit of FIG. 7 will be described. As an example, it is assumed that the power supply voltage Vdd applied to the power supply terminal 8 is set to 3 V, the control voltage Vc applied to the control terminal 9 is set to 3 V, and the reference voltage Vref applied to the reference terminal 11 is set to 1.5 V. Also, the threshold voltage Vp of the field effect transistors 26 and 32 is -0.6 V
And

At this time, the control terminal 82d of the switch 82
And a control terminal 5d of the changeover switch 5 includes a control terminal 9
The control voltage Vc of 3 V is supplied, and the reference terminal 82 e of the switch 82 and the reference terminal 5 e of the changeover switch 5 are supplied with the reference voltage Vref of 1.5 V from the reference terminal 11. At this time, the relationship of Vc> Vref is established, and conduction between the common terminal 5a and the switching terminal 5b of the switch 5 is conducted. In addition, the relationship of Vc> Vref + | Vp | is established, and one terminal 82a of the switch 82 and the other terminal 82
b, the common terminal 5a of the changeover switch 5 and the changeover terminal 5
c and open.

In this state, the signal input to the high-frequency amplifier circuit is input from the signal input terminal 1 to the amplifier 3, and
The switching terminal 5 of the changeover switch 5 is amplified by the amplifier 3
The signal sequentially passes between the terminal b and the common terminal 5 a and is output from the signal output terminal 6.

Here, the gain of the amplifier 3 is G, the switch 8
2, between the one terminal 82a and the other terminal 82c, between the common terminal 5a and the switching terminal 5b of the changeover switch 5, and between the common terminal 5a
-Let the signal loss between the switching terminals 5c be L, respectively.

In this case, the gain P of the high-frequency amplifier shown in FIG.
G1 is expressed by the following equation.

PG1 = GL (3) Next, the power supply voltage Vdd applied to the power supply terminal 8 is set to 0V, the control voltage applied to the control terminal 9 is set to 0V, and the reference terminal 11 is set.
Is set to 1.5V.

At this time, the control terminal 82d of the switch 82
And a control terminal 5d of the changeover switch 5 includes a control terminal 9
The control voltage Vc of 0 V is supplied, and the reference terminal 82 e of the switch 82 and the reference terminal 5 e of the changeover switch 5 are supplied with the reference voltage Vref of 1.5 V from the reference terminal 11. At this time, the relationship of Vc <Vref is established, and conduction is established between one terminal 82a and the other terminal 82c of the switch 82 and between the common terminal 5a and the switching terminal 5c of the changeover switch 5. Further, the relationship of Vc <Vref− | Vp | is established, and the common terminal 5a and the switching terminal 5b of the changeover switch
Open between.

In this state, the signal input to the high-frequency amplifier circuit is transmitted from the signal input terminal 1 to one terminal 82a of the switch 82 and the other terminal 82c, to the filter 4, and further to the switching terminal 5c of the switching switch 5 to the common terminal. The signal sequentially passes through the terminals 5 a and is output from the signal output terminal 6.

Here, assuming that the passing loss of the filter is L2, the gain PG2 of the high frequency amplifier circuit of FIG. 7 is expressed by the following equation.

PG 2 = −2 × L−L 2 (4) The high-frequency amplifier circuit of FIG. 7 switches the control voltage Vc applied to the control terminal 9 to make it clear from the equations (3) and (4). As described above, the gain can be changed by G + L + L2.

The reference voltage applied to the source terminal of the first field effect transistor 26 is increased by a value corresponding to the threshold voltages of the first and second field effect transistors 26 and 32 to the second field effect transistor 32. Can be set higher than the reference voltage applied to the gate terminal.

For example, if the threshold voltage is -0.6 V
, The reference voltage Vref1 applied to the source terminal of the first field effect transistor 26 is set to 1.8 V,
Assuming that the reference voltage Vref2 applied to the gate terminal of the field effect transistor 32 is 1.2 V, the voltage range in which the first and second field effect transistors 26 and 32 are in an intermediate state between ON and OFF can be overlapped. That is, the first
The voltage at which the ON of the field effect transistor 26 is determined and the voltage at which the OFF of the second field effect transistor 32 is determined can be the same voltage. The voltage at which ON of the second field-effect transistor 32 is determined can be the same voltage.

It is necessary to set the control voltage so as to avoid a voltage range where the first and second field effect transistors 26 and 32 are in an intermediate state between on and off. Second field effect transistor 2
The first and second field-effect transistors 26 and 32 are compared with the case where the reference voltage applied to
The setting range of the control voltage for turning on and off the power supply can be widened.

As described above, when the same reference voltage is used, when the reference voltage is 1.5 V, the upper value of the control voltage Vc needs to be set to a value exceeding 2.1 V, and the control voltage Vc Was required to be set to a value of less than 0.9 V, but as described above, one of the reference voltages was 1.8 V,
Assuming that the other voltage is 1.2 V, the upper value of the control voltage Vc may be a value exceeding 1.8 V, and the lower value of the control voltage Vc may be set to a value less than 1.2 V.

In FIG. 7, when the filter having the configuration shown in FIG. 3 is used as in the first embodiment, the filter having such a configuration has a frequency lower than the frequency set by the values of inductor 44 and capacitor 45. Frequency signals are attenuated and pass through.

When the filter is configured as described above,
When the capacitance value of the capacitor 31 or the capacitor 34 in FIG. 2 of the changeover switch 5 in FIG. Alternatively, the capacitor 34 or both of them can be substituted for the capacitor 45. With this configuration, the capacitor 45 becomes unnecessary,
The number of components constituting the circuit can be reduced.

In FIG. 7, when the amplifier 3 having the configuration shown in FIG. 6 is used similarly to the first embodiment, and when the filter having the configuration shown in FIG. 4 is used, the filter thus configured has an inductor. Signals at frequencies higher than the frequency set by the values of 55 and the capacitor 54 are attenuated and passed. Here, the inductor 55 in FIG.
In FIG. 7, although not shown, it is inserted immediately after the signal input terminal 1 as a matching circuit.

When the filter is configured as described above,
7, the supply of the power supply voltage Vdd to the power supply terminal 8 is stopped or interrupted, and the parasitic capacitance 81 between the gate and the source of the FET 79 of the amplifier 3 is replaced by the capacitor 5 in FIG.
It may be used instead of 4. With this configuration, the capacitor 54 becomes unnecessary, and the number of components constituting the circuit can be reduced.

In FIG. 7, when the filter shown in FIG. 5 is used as in the first embodiment, the filter thus configured is set by the values of the inductor 65, the capacitor 66, the inductor 67, and the capacitor 68. Signals of lower and higher frequencies are attenuated and pass.

When the filter is configured as described above,
The capacitor 31 in FIG. 2 of the changeover switch 5 in FIG.
Alternatively, when the capacitance value of the capacitor 31 or the capacitor 34 is set such that the combined capacitance value of the capacitor 34 or both of them corresponds to the capacitance value of the capacitor 68, the capacitor 68 is substituted for the capacitor 31 or the capacitor 34 or both. It is possible to do. With this configuration, the capacitor 68 becomes unnecessary, and the number of components constituting the circuit can be reduced.

When the filter is constructed in this manner, the supply of the power supply voltage Vdd to the power supply terminal 8 in FIG. 7 is stopped or cut off.
The parasitic capacitance 81 between the sources is replaced by the capacitor 66 in FIG.
May be used instead of. With this configuration, the capacitor 66 becomes unnecessary, and the number of components constituting the circuit can be reduced.

In FIG. 7, when the amplifier shown in FIG. 6 is used, the combined capacitance value of the capacitor 25 and / or the capacitor 28 in FIG. 2 of the changeover switch 5 of FIG. When the capacitance value of the capacitor 25 or the capacitor 28 is set correspondingly, it is possible to substitute the capacitor 25 or the capacitor 28 or both of them as the capacitor 78. With this configuration, the capacitor 78 becomes unnecessary, and the number of components constituting the circuit can be reduced.

Also, as shown in FIG.
One terminal 82a may be connected to the gate terminal of the FET 79 in FIG. 6 instead of the signal input terminal 1.

In the configuration shown in FIG. 14, when a filter having the configuration shown in FIG. 4 is used, a signal having a frequency higher than the frequency set by the values of inductor 55 and capacitor 54 is attenuated in the filter configured as described above. Pass through.

When the filter is configured as described above,
The parasitic capacitance 81 between the gate and the source of the FET 79 of the amplifier 3 in which the supply of the power supply voltage Vdd to the power supply terminal 8 in FIG. 14 is stopped or cut off may be used instead of the capacitor 54 in FIG. With this configuration, the capacitor 54 becomes unnecessary, and the number of components constituting the circuit can be reduced.

When the filter is configured as described above,
The inductor 75 of FIG. 14 is replaced with the inductor 55 of FIG.
May be used instead of. With this configuration, the inductor 55 becomes unnecessary, and the number of components constituting the circuit can be reduced.

A low-pass filter similar to that shown in FIG. 4 can be formed by the inductor 75 and the parasitic capacitance 81. When a low-pass filter having the configuration shown in FIG. A band-pass filter similar to that shown in FIG.

As shown in FIG. 14, one terminal 82a of the switch 82 is not the signal input terminal 1 but the F terminal.
When a filter having the configuration shown in FIG. 5 is used in the configuration connected to the gate terminal of the ET 79, the frequency of the filter configured as described above is lower than the frequency set by the values of the inductor 65, the capacitor 66, the inductor 67, and the capacitor 68. Frequency and high frequency signals are attenuated and pass.

When the filter is configured as described above,
The capacitor 31 in FIG. 2 of the changeover switch 5 in FIG.
Alternatively, when the capacitance value of the capacitor 31 or the capacitor 34 is set so that the combined capacitance value of the capacitor 34 or both of them corresponds to the capacitance value of the capacitor 68, the capacitor 68 is substituted for the capacitor 31 or the capacitor 34 or both. It is possible to do. With this configuration, the capacitor 68 becomes unnecessary,
The number of components constituting the circuit can be reduced.

When the filter is configured as described above,
The parasitic capacitance 81 between the gate and the source of the FET 79 of the amplifier 3 in which the supply of the power supply voltage Vdd to the power supply terminal 8 in FIG. 14 is stopped or cut off may be used instead of the capacitor 66 in FIG. With this configuration, the capacitor 66 becomes unnecessary, and the number of components constituting the circuit can be reduced.

When the filter is configured as described above,
The inductor 75 of FIG. 14 is replaced with the inductor 65 of FIG.
May be used instead of. With this configuration, the inductor 65 becomes unnecessary, and the number of components constituting the circuit can be reduced.

According to this embodiment, since the amplifier 3 and the filter 4 are selectively operated, when the input signal strength is strong, the gain of the signal in the desired frequency band is reduced. At this time, the filter 3 is operated. Therefore, the interference wave can be attenuated by the filter 4, and when used in a mobile phone terminal, the interference wave entering the down converter can be sufficiently suppressed, and the deterioration of the communication quality at low gain can be prevented. Can be. Therefore, for example, when used in a mobile phone terminal, a high-precision band-pass filter provided on the input side of the down-converter is not required, and downsizing and price reduction can be achieved. Further, the local oscillation signal leaking from the down converter can be sufficiently attenuated by the filter, and the emission of unnecessary radio waves to the outside can be sufficiently reduced.

In the first mode, a predetermined power supply voltage is supplied to the amplifier 3, and in the second mode, the supply of the power supply voltage to the amplifier 3 is stopped or cut off so that no operating current flows to the amplifier 3. Then, when the input signal strength is strong and the gain needs to be reduced, the gain can be reduced and the current consumption of the amplifier 3 can be reduced to almost 0 by setting the second mode. For example, when used in a mobile phone terminal, the standby time of the mobile phone terminal can be lengthened.

If the control voltage is set to a high voltage in the first mode, the control voltage is set to a low voltage in the second mode, and the control voltage is supplied to the amplifier 3 as a power supply voltage, the control of the power supply and the gain of the amplifier 3 Does not require a separate power supply, thereby simplifying the circuit configuration. For example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

[0188]

According to the high-frequency amplifier circuit of the first aspect, when the input signal strength is high, the gain of the signal in the desired frequency band is reduced.
The interfering wave can be attenuated by the filter, and when used in a mobile phone terminal, the interfering wave entering the down converter can be sufficiently suppressed, and the deterioration of the communication quality at low gain can be prevented. Therefore, for example, when used in a mobile phone terminal, a high-precision band-pass filter provided on the input side of the down-converter is not required, and downsizing and price reduction can be achieved. Further, the local oscillation signal leaking from the down converter can be sufficiently attenuated by the filter, and the emission of unnecessary radio waves to the outside can be sufficiently reduced.

According to the high frequency amplifier circuit of the second aspect,
When the input signal strength is strong and it is necessary to lower the gain, setting the second mode can lower the gain and reduce the current consumption of the amplifier to almost zero. For example, when used in a mobile phone terminal, the standby time of the mobile phone terminal can be lengthened.

According to the high frequency amplifier circuit of the third aspect,
The power supply of the amplifier and the power supply for controlling the gain are not separately required, and the circuit configuration can be simplified. For example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

According to the high frequency amplifier circuit of the fourth aspect,
Since the element constituting the filter can be formed on a semiconductor chip or by a small chip component, the above function can be realized with a smaller size. For example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

According to the high frequency amplifier circuit of the fifth aspect,
Since the amplifier is used as an element constituting a filter, the above function can be realized with a smaller size. For example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

According to the high frequency amplifier circuit of the sixth aspect,
The function selection circuit can be realized with a simple configuration including only the first and second changeover switches. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

According to the high frequency amplifier circuit of the seventh aspect,
The function selection circuit can be realized with a simple configuration including only switches and changeover switches. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

According to the high frequency amplifier circuit of the eighth aspect,
An effect similar to that of the high-frequency amplifier circuit according to the sixth or seventh aspect is obtained.

According to the high frequency amplifier circuit of the ninth aspect,
Since the element constituting the filter can be formed on a semiconductor chip or by a small chip component, the above function can be realized with a smaller size. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

According to the high frequency amplifier circuit of the tenth aspect, since the element constituting the filter can be formed on a semiconductor chip or by a small chip component, the above function can be realized with a smaller size. it can. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

According to the high frequency amplifier circuit of the eleventh aspect, since the element constituting the filter can be formed on a semiconductor chip or by a small chip component, the above function can be realized with a smaller size. it can. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

According to the high frequency amplifier circuit of the twelfth aspect, since the input matching circuit and the parasitic capacitance of the field effect transistor whose operation is stopped are used as components of the filter, the components constituting the filter are the components of the amplifier. And the number of parts can be reduced. Therefore, for example, when used for a mobile phone terminal, the size and weight of the mobile phone terminal can be reduced.

According to the high frequency amplifying circuit of the thirteenth aspect, the same effect as that of the high frequency amplifying circuit of the twelfth aspect is obtained.

According to the high frequency amplifier circuit of the present invention, the first mode and the second mode can be switched by one control voltage, and the mode switching can be easily controlled.

According to the high frequency amplifier circuit of the present invention, the first and second modes can be switched by one control voltage, and the mode switching can be easily controlled.

According to the high frequency amplifier circuit of claim 16, the input terminal of the reference voltage and the output terminal of the amplifier can be shared, so that the number of terminals can be reduced.

According to the portable telephone terminal of the seventeenth aspect,
If the input signal strength is strong, the gain of the signal in the desired frequency band is reduced.However, since the filter is operated at this time, the interference wave can be attenuated by the filter, and the interference wave entering the down converter should be sufficiently suppressed. Thus, it is possible to prevent deterioration of speech quality at the time of low gain. Therefore, a high-precision bandpass filter is not required as the bandpass filter provided on the input side of the downconverter, and a reduction in size and cost can be achieved. Further, the local oscillation signal leaking from the down converter can be sufficiently attenuated by the filter, and the emission of unnecessary radio waves to the outside can be sufficiently reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a high-frequency amplifier circuit according to a first embodiment of the present invention.

FIG. 2 shows a configuration of first and second changeover switches in a high-frequency amplifier circuit according to a first embodiment of the present invention, and a configuration of a changeover switch in a high-frequency amplifier circuit according to a second embodiment of the present invention. It is a circuit diagram.

FIG. 3 is a block diagram showing a first configuration of a filter according to the first and second embodiments of the present invention.

FIG. 4 is a block diagram showing a second configuration of the filter according to the first and second embodiments of the present invention.

FIG. 5 is a block diagram showing a third configuration of the filter according to the first and second embodiments of the present invention.

FIG. 6 is a block diagram illustrating a configuration of an amplifier according to the first and second embodiments of the present invention.

FIG. 7 is a block diagram illustrating a configuration of a high-frequency amplifier circuit according to a second embodiment of the present invention.

FIG. 8 is a circuit diagram showing a configuration of a switch in a high-frequency amplifier circuit according to a second embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration of a wireless unit of a conventional mobile phone terminal.

FIG. 10 is a block diagram showing a configuration of a receiving unit and a duplexer unit in a wireless unit of a conventional mobile phone terminal.

FIG. 11 is a block diagram showing a configuration of a conventional high frequency amplifier circuit having a built-in gain control function.

FIG. 12 is a graph showing the relationship between gain (power amplification factor) and frequency in a conventional high frequency amplifier circuit having a built-in gain control function.

FIG. 13 is a graph showing the relationship between the signal strength and the frequency of each unit at the time of high gain and at the time of low gain in a conventional high-frequency amplifier circuit having a built-in gain control function.

FIG. 14 is a block diagram illustrating a configuration of a high-frequency amplifier circuit according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal input terminal 2 Changeover switch 3 Amplifier 4 Filter 5 Changeover switch 6 Signal output terminal 7 GND terminal 8 Power supply terminal 9 Control terminal 11 Reference terminal 21 Common terminal 22 Switching terminal 23 Switching terminal 25 Capacitor 26 Field effect transistor 27 Resistance 28 Capacitor 29 Resistance 30 Resistance 31 Capacitor 32 Field effect transistor 33 Resistance 34 Capacitor 35 Resistance 36 Resistance 39 Reference terminal 40 Control terminal 41 Input terminal 42 Output terminal 43 GND terminal 44 Inductor 45 Capacitor 51 Input terminal 52 Output terminal 53 GND terminal 54 Capacitor 55 Inductor 61 Input terminal 62 Output terminal 63 GND terminal 64 GND terminal 65 Inductor 66 Capacitor 67 Inductor 68 Capacitor 71 Input terminal 72 Output terminal 73 Power supply terminal Child 74 GND terminal 75 Inductor 76 Inductor 77 Capacitor 78 Capacitor 79 Field effect transistor 80 GND terminal 81 Parasitic capacitance 82 Switch 91 Input terminal 92 Output terminal 101 Signal output terminal 102 Bandpass filter 103 Downconverter 104 Voltage controlled oscillator 105 Bandpass filter 106 High frequency amplifier circuit 107 Antenna 108 Signal input terminal 109 Duplexer 200 Transmitter 201 Upconverter 202 High frequency amplifier circuit 203 High output high frequency amplifier circuit 204 Isolator 300 Receiver 301 High frequency amplifier circuit 302 Bandpass filter 303 Downconverter 304 Bandpass filter 400 Synthesizer section 401 TCXO 402 PLL 403 VCO 500 Duplexer 501 Ann Na 502 duplexer 601 signal input terminal 602 changeover switch 603 amplifier 604 changeover switch 605 signal output terminal 606 the power supply terminal 607 a control terminal

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsushi Tara 1-1, Kochicho, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. F-term (reference) 5J092 AA01 AA53 CA27 CA93 FA14 FA18 HA09 HA25 HA29 HA33 HA39 HA40 KA42 KA44 KA46 KA48 MA22 SA01 SA13 TA01 TA03 VL01 VL02 VL03 VL05 VL07 5J100 AA14 BA01 BB16 BC07 DA06 FA02 5K052 AA01 BB01 CC06 DD05 EE11 FF05 GG13

Claims (16)

[Claims] A signal input terminal and a signal output terminal; and a high-frequency signal provided between the signal input terminal and the signal output terminal, which is input to the signal input terminal, and output to the signal output terminal. An amplifier that supplies a desired frequency component of the high-frequency signal that is provided between the signal input terminal and the signal output terminal and that is input to the signal input terminal, as an output signal to the signal output terminal; A filter for attenuating unnecessary frequency components, an output signal from the amplifier is taken out from the signal output terminal in a first mode according to a control voltage, and an output signal from the filter is output to the signal output in a second mode. A high-frequency amplifier circuit including a function selection circuit for extracting from a terminal. In a first mode, a predetermined power supply voltage is supplied to the amplifier, and in a second mode, the supply of the power supply voltage to the amplifier is stopped or cut off so that no operating current flows to the amplifier. The high-frequency amplifier circuit according to claim 1. 3. The method according to claim 1, wherein the control voltage is set to a high voltage in the first mode, and set to a low voltage in the second mode, and the control voltage is supplied to the amplifier as a power supply voltage. High frequency amplifier circuit. 4. The high frequency amplifier circuit according to claim 1, wherein the filter comprises a capacitor and an inductor. 5. The method according to claim 2, wherein when the filter is selectively operated in the second mode, a parasitic capacitance of the amplifier is used as one of the capacitors of the filter.
A high-frequency amplifier circuit as described in the above. 6. A function selecting circuit connects a common terminal to a signal input terminal, connects one switching terminal to an input terminal of an amplifier, connects the other switching terminal to an input terminal of a filter, and responds to a control voltage. A first switch, which is switched by a switch, and one switch terminal connected to the output terminal of the amplifier,
A second switch connected to the output terminal of the filter, the second switch being switched in accordance with the control voltage, when the first switch is switched to one of the switch terminals; The second switching switch is switched to one switching terminal, and the second switching switch is switched to the other switching terminal when the first switching switch is switched to the other switching terminal. Item 3. The high frequency amplifier circuit according to item 1, 2 or 3. 7. A switch for connecting one terminal to a signal input terminal, connecting the other terminal to an input terminal of a filter, and connecting and disconnecting the switch according to a control voltage, and a function selection circuit to an output terminal of the amplifier. One switching terminal is connected, the other switching terminal is connected to the output terminal of the filter, and the switching is performed according to the control voltage. The switching switch is opened when the switch is opened. 4. The high-frequency amplifier circuit according to claim 1, wherein the switching terminal is switched to the other switching terminal side, and when the switch is turned on, the switching switch is switched to the other switching terminal side. 8. The high-frequency amplifier circuit according to claim 6, wherein the changeover switch comprises first and second unit switches having one terminal connected in common and conducting / opening in opposite directions. 9. An inductor in which a filter has one terminal connected to an input terminal and the other terminal grounded at a high frequency,
8. The high-frequency amplifier circuit according to claim 6, further comprising a capacitor having one terminal connected to the input terminal and the other terminal connected to the output terminal. 10. An inductor in which a filter has one terminal connected to an input terminal and the other terminal connected to an output terminal, and one terminal connected to the other terminal of the inductor and the other terminal grounded at high frequency. 8. The high-frequency amplifier circuit according to claim 6, wherein said high-frequency amplifier circuit comprises a capacitor. 11. A filter having a first inductor having one terminal connected to an input terminal, and a first inductor having one terminal connected to the other terminal of the first inductor and the other terminal grounded at a high frequency. A first capacitor, a second inductor having one terminal connected to the other terminal of the first inductor and the other terminal grounded at a high frequency, and one terminal connected to the other terminal of the first inductor. 8. The high-frequency amplifier circuit according to claim 6, further comprising a second capacitor connected to the output terminal and the other terminal connected to the output terminal. 12. An amplifier comprising: at least one field effect transistor; and an input matching circuit provided between a signal input terminal and a gate terminal of the field effect transistor, wherein the function selection circuit includes a gate of the field effect transistor. One terminal is connected to the filter, the other terminal is connected to the input terminal of the filter, a switch that conducts and opens according to the control voltage, and one switching terminal is connected to the output terminal of the amplifier, and the output terminal of the filter is connected. And a switching switch for performing switching in accordance with the control voltage. In a second mode, the parasitic capacitance of the input matching circuit and the parasitic capacitance of the field effect transistor stopped operating. 3. The high-frequency amplifier circuit according to claim 2, wherein the high-frequency amplifier circuit is used as a component of a filter. 13. The high-frequency amplifier circuit according to claim 12, wherein the input matching circuit includes an inductor having one end connected to the signal input terminal and the other end connected to the gate terminal of the field effect transistor. 14. The first and second unit switches each include a field-effect transistor having one terminal connected to one of a drain terminal and a source terminal and the other terminal connected to the other of a source terminal and a drain terminal. The field-effect transistor that forms the first unit switch has a control voltage applied to a source terminal and a reference voltage applied to a gate terminal, and the field-effect transistor that forms the second unit switch has a gate. 9. The high-frequency amplifier circuit according to claim 8, wherein a control voltage is applied to the terminal and a reference voltage is applied to the source terminal. 15. A changeover switch includes first and second unit switches that commonly connect one terminal and conduct and open in opposite directions, and each of the first and second unit switches has a drain terminal connected to one terminal. Alternatively, a field-effect transistor in which one of the source terminals is connected and the other of the source terminal and the drain terminal is connected to the other terminal, and the field-effect transistor configuring the first unit switch,
A control voltage is applied to the source terminal, a reference voltage is applied to the gate terminal, and a control voltage is applied to the gate terminal and a reference voltage is applied to the source terminal of the field-effect transistor constituting the second unit switch. The switch has a field-effect transistor in which one of a drain terminal and a source terminal is connected to one terminal and the other of the source terminal and the drain terminal is connected to the other terminal. 8. The high-frequency amplifier circuit according to claim 7, wherein the control voltage is applied to a gate terminal and the reference voltage is applied to a source terminal. 16. A mobile phone terminal having a built-in high-frequency amplifier circuit for high-frequency amplification of a reception signal, wherein the high-frequency amplifier circuit includes a signal input terminal and a signal output terminal; the signal input terminal and the signal output terminal; An amplifier provided between the signal input terminal and the signal output terminal, for amplifying the reception signal input to the signal input terminal and supplying the amplified signal as an output signal to the signal output terminal; A filter that supplies a desired frequency component of the received signal input to the signal input terminal to the signal output terminal as an output signal, and attenuates an unnecessary frequency component. An output signal is taken out from the signal output terminal, and an output signal from the filter is taken out from the signal output terminal in the second mode. Terminal.