JP3679400B2 - High frequency switch, high frequency switch / amplifier circuit, and mobile communication terminal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-frequency switch that is provided in a high-frequency circuit unit of a transmission unit of a mobile communication terminal such as a mobile phone terminal and switches a signal path of a high-frequency signal.
[0002]
The present invention also relates to a high frequency switch / amplifier circuit for switching the signal path of a high frequency signal and amplifying the high frequency signal.
[0003]
Furthermore, the present invention relates to a mobile communication terminal using the above-described high-frequency switch or high-frequency switch / amplifier circuit.
[0004]
In particular, the present invention relates to a high-frequency switch and a high-frequency switch / amplifier circuit that switch a path of a high-frequency signal by a control voltage.
[0005]
[Prior art]
Recently, in the mobile communication field, integrated mobile phone terminals that integrate a plurality of communication methods as communication methods are becoming mainstream. For example, a mobile phone terminal that supports both the W-CDMA (Wide Band Code Division Multiple Access) method and the PDC (Personal Digital Cellular) method can be considered. Such an integrated mobile phone terminal can take advantage of the advantages such as high data communication speed in the W-CDMA system and the wide service area in the PDC system, and is expected to rapidly spread in the future. ing.
[0006]
Since the frequency used as a carrier wave is different between the W-CDMA system and the PDC system, it is necessary to create two high-frequency circuit blocks for the W-CDMA system and the PDC system. In addition, the design of the high-frequency circuit block is regarded as important in realizing the miniaturization of the mobile communication terminal and the reduction of the operating current of the high-frequency circuit block.
[0007]
Hereinafter, a conventional typical mobile phone terminal that supports a plurality of communication methods such as the PDC method and the W-CDMA method will be described.
[0008]
FIG. 4 is a block diagram showing a configuration of a radio unit of a conventional typical mobile phone terminal. In FIG. 4, the radio unit of the mobile phone terminal includes a transmission unit 200, a reception unit 300, a synthesizer unit 400, and a duplexer unit 500.
[0009]
The transmission unit 200 sets the modulation signal input (intermediate frequency modulation signal) of the intermediate frequency (for example, 600 MHz) to the transmission frequency (about 900 MHz in the case of the PDC system, and about 1.9 GHz in the case of the W-CDMA system). An up-converter 201 for conversion, a high-frequency amplifier circuit 202 of variable gain for amplifying an output signal (1 mW or less) of the up-converter 201 to a maximum of about 10 mW, a high-frequency switch 203 for switching and using a band-pass filter according to a transmission frequency, A band-pass filter 204 and a band-pass filter 207 for extracting signals in the transmission wave band, and a high-output high-frequency amplifier circuit 205 having a fixed gain that amplifies a high-frequency signal (10 mW or less) output from the band-pass filter 204 to a maximum of about 1 W. , Transmit the output of high-output high-frequency amplifier circuit 205 as radio waves Therefore, the isolator 206 supplied to the duplexer unit 500, the high-power high-frequency amplifier circuit 208 having a fixed gain that amplifies the high-frequency signal (10 mW or less) output from the band-pass filter 207 up to about 1 W at maximum, and the high-output high-frequency amplifier circuit 208 The isolator 209 is supplied to the duplexer unit 500 in order to transmit the output as a radio wave.
[0010]
The receiving unit 300 amplifies the received signal received by the duplexer unit 500 at a high frequency and mixes the received signal with a local oscillation signal supplied from the synthesizer unit 400, and outputs an intermediate signal from the output signal of the front end IC 301. A band-pass filter 302 that extracts a frequency signal is used.
[0011]
The synthesizer unit 400 includes a temperature controlled crystal oscillator (TCXO) 401, a phase locked loop (PLL) circuit 402, and a voltage controlled oscillator (VCO) 403.
[0012]
The duplexer unit 500 includes an antenna 501, an antenna 502, and a duplexer 503.
[0013]
In this radio unit, the up-converter 201 and the high-frequency amplifier circuit 202 are shared in order to support a plurality of communication systems such as the PDC system and the W-CDMA system and to reduce the size of the high-frequency circuit block of the mobile communication terminal. ing. On the other hand, the band-pass filters 204 and 207, the high-output high-frequency amplifier circuits 205 and 208, and the isolators 206 and 209 require circuit blocks corresponding to the respective communication frequencies. Therefore, the high frequency switch 203 is required to select a circuit block corresponding to the communication frequency.
[0014]
FIG. 5 is a block diagram showing a configuration of a radio unit of another conventional mobile phone terminal. In FIG. 5, an intermediate frequency modulation signal in which sound or the like is modulated is input to a signal input terminal 101. The up-converter 103 receives the intermediate frequency modulation signal from the signal input terminal 101 and the local oscillation signal from the oscillator 102. As a result, the up-converter 103 converts the intermediate frequency into a transmission frequency. Specifically, the up-converter 103 converts the intermediate frequency into the transmission frequency by mixing the intermediate frequency signal (intermediate frequency modulation signal) and the local oscillation signal from the oscillator 102.
[0015]
Here, when the frequency of the intermediate frequency modulation signal input to the up-converter 103 is fif, the local oscillation frequency of the oscillator 102 is flo, and the frequency of the transmission signal is fc, the frequency of the transmission signal and the frequency of the intermediate frequency modulation signal are What is local oscillation frequency?
fc = flo ± fif
It becomes a relationship. Therefore, up-converter 103 outputs a transmission signal having frequency fc. Examples of the intermediate frequency and transmission signal frequency are as described above. Further, by changing the oscillation frequency of the oscillator 102, it is possible to synthesize transmission waves corresponding to a plurality of transmission frequencies such as the PDC method and the W-CDMA method.
[0016]
The high frequency amplifier circuit 104 has a built-in gain control function and amplifies a signal having a transmission frequency up to about 10 mW. The high frequency switch 105 is used to select a high frequency circuit corresponding to the communication frequency.
[0017]
Here, the band-pass filter 106, the high-output high-frequency amplifier circuit 107, and the isolator 108 are each defined as a high-frequency circuit that is used for the PDC system, and the band-pass filter 109, the high-output high-frequency amplifier circuit 110, and the isolator 111 are each W-CDMA. It is defined as a high-frequency circuit used in the system.
[0018]
In the case of the PDC system, the output signal of the high frequency amplifier circuit 104 is output from the terminal 105 a of the high frequency switch 105 to the terminal 105 b and input to the band pass filter 106. The band pass filter 106 extracts and outputs only the signal of the transmission wave band from the input signal. The high-output high-frequency amplifier circuit 107 amplifies the output signal (transmission frequency signal) of the bandpass filter 106 to about 1 W at maximum. The output of the high-output high-frequency amplifier circuit 107 is input from the isolator 108 to the terminal 112a of the duplexer 112.
[0019]
In the case of the W-CDMA system, the output signal of the high frequency amplification circuit 104 is output from the terminal 105 a of the high frequency switch 105 to the terminal 105 c and input to the band pass filter 109. The band pass filter 109 extracts and outputs only the signal in the transmission wave band from the input signal. The high-output high-frequency amplifier circuit 110 amplifies the output signal (transmission frequency signal) of the band-pass filter 109 to a maximum of about 1 W. The output of the high-output high-frequency amplifier circuit 110 is input from the isolator 111 to the terminal 112b of the duplexer 112.
[0020]
The duplexer 112 sends the transmission signal output from the isolator 108 to the antenna 113, sends the reception signal received by the antenna 113 to the signal output terminal 115, sends the transmission signal output from the isolator 111 to the antenna 114, and The received signal is sent to the signal output terminal 116.
[0021]
Here, in the high-frequency circuit block shown in FIG. 5, the antennas 113 and 114 are selectively used according to the communication method, the antenna 113 is used in the PDC method, and the antenna 114 is used in the W-CDMA method. Specifically, the duplexer 112 has the following functions. That is, a signal in the direction from the terminal 112a to the terminal 112c is allowed to pass, and a signal in the direction from the terminal 112a to another terminal is blocked. Further, a signal in the direction from the terminal 112b to the terminal 112d is allowed to pass, and a signal in the direction from the terminal 112b to another terminal is blocked. Further, a signal in the direction from the terminal 112c to the terminal 112e is allowed to pass, and a signal in the direction from the terminal 112c to another terminal is blocked. Further, a signal in the direction from the terminal 112d to the terminal 112f is allowed to pass, and a signal in the direction from the terminal 112d to another terminal is blocked. Further, signals in the direction from the terminal 112e and the terminal 112f to the other terminals are blocked.
[0022]
In the configuration shown in FIG. 5, the high-frequency circuit block is selected by the high-frequency switch 105, thereby realizing a reduction in the size of the high-frequency circuit block in a mobile communication terminal such as a mobile phone terminal that supports a plurality of communication methods. . In order to realize further miniaturization of the high-frequency circuit block of the mobile communication terminal in the future, it is necessary to integrate circuit blocks composed of individual elements such as a high-frequency amplifier circuit and a high-frequency switch.
[0023]
Next, the high frequency switch used in the high frequency circuit block of the mobile communication terminal will be described.
[0024]
A MESFET is used as a high-frequency switch used in a high-frequency circuit block, and a switch operation has been realized by using an ON resistance and an OFF resistance of the FET. In general, the MESFET is a depletion type FET, and the threshold value is a negative voltage. When a high frequency switch is configured using MESFETs, the source electrode and drain electrode of the FET are used as two signal electrodes, and the gate electrode of the FET is used as a control electrode. When the source electrode and the drain electrode of the FET are each set to 0V, the gate electrode may be set to 0V in order to turn the FET on. To turn the FET off, the gate electrode is set to the threshold value. A lower voltage may be set.
[0025]
FIG. 6 shows an SPDT (Single Pole Dual Through) switch circuit using an FET as a high frequency switch. In the SPDT switch circuit of FIG. 6, the source electrode of the field effect transistor 131 that is a switch element is connected to the signal input terminal 125 via the capacitor 151, and the drain electrode of the field effect transistor 131 is connected to the signal output terminal 127 via the capacitor 152. It is connected to the. Further, the source electrode of the field effect transistor 132 that is a switch element is connected to the signal input terminal 125 via the capacitor 153, and the drain electrode of the field effect transistor 132 is connected to the signal output terminal 128 via the capacitor 154.
[0026]
The source electrode of the field effect transistor 131 is connected to the control terminal 124 via the resistor 141. The gate electrode of the field effect transistor 132 is connected to the control terminal 124 via the resistor 142.
[0027]
The source electrode and the drain electrode of the field effect transistor 131 are connected to each other via the resistor 146 and have the same potential. Further, the source electrode and the drain electrode of the field effect transistor 132 are connected to each other via the resistor 147 and have the same potential.
[0028]
A series circuit of resistors 143 and 144 is connected between the power supply terminal 121 and the ground terminal 122, and a connection point between the resistors 143 and 144 is a reference voltage terminal 123. The gate electrode of the field effect transistor 131 is connected to the reference voltage terminal 123 via the resistor 145. The source electrode of the field effect transistor 132 is directly connected to the reference voltage terminal 123.
[0029]
The reference voltage generation circuit includes resistors 143 and 144 connected between the power supply terminal 121 and the ground terminal 122. Capacitors 151 to 154 are inserted to remove direct current components. The resistors 141, 142, 145, 146, and 147 have high resistance values. The control terminal 124 is a terminal for controlling the operation state of the switch circuit.
[0030]
The resistors 143 and 144 constituting the reference voltage generation circuit have the same resistance value, and the voltage output from the reference voltage terminal 123 when the power supply voltage input to the reference voltage generation circuit is Vdd. Vref is Vdd / 2.
[0031]
For example, in FIG. 6, when a voltage of 3V is applied as the voltage Vdd to the power supply terminal 121 and the ground terminal 122 is grounded, a voltage of 1.5V is generated as the reference voltage Vref at the reference voltage terminal 123 by the reference voltage generation circuit. To do. Here, when a voltage of 0 V is applied to the control terminal 124 as the control voltage Vc, a voltage of 0 V is applied to the drain electrode and the source electrode of the field effect transistor 131 constituting the switch element, respectively, A voltage of 1.5V is applied. In addition, a voltage of 1.5 V is applied to the drain electrode and the source electrode of the field effect transistor 132 constituting the switch element, and a voltage of 0 V is applied to the gate electrode.
[0032]
Here, assuming that the threshold value Vth of the field effect transistors 131 and 132 is −0.7 V, in the field effect transistor 131, the potential of the gate electrode is higher than that of the source electrode and the drain electrode and becomes 0 V or more. Yes. As a result, the impedance between the source electrode and the drain electrode of the field effect transistor 131 becomes low, and the field effect transistor 131 is in the ON state. At this time, in the field effect transistor 132, the gate electrode has a potential lower than the potential of the source and drain electrodes by a threshold Vth of the field effect transistor 132. The impedance between the drain electrodes is high impedance, and the field effect transistor 132 is in the OFF state.
[0033]
In this state, when a high frequency signal is input from the signal input terminal 125, the high frequency signal is output from the signal output terminal 127 through the low-impedance field effect transistor 131. Further, the high frequency signal input from the signal input terminal 125 is blocked by the high-impedance field effect transistor 132, and no high frequency signal is output from the signal output terminal 128. As a result, the high frequency signal input from the signal input terminal 125 is output from the signal output terminal 127.
[0034]
Next, in FIG. 6, when a voltage of 3V is applied to the power supply terminal 121 as the power supply voltage Vdd and the ground terminal 122 is grounded, a voltage of 1.5V is applied to the reference voltage terminal 123 by the reference voltage generation circuit as a reference voltage Vref. Will occur. Here, when a voltage of 3V is applied as the control voltage Vc to the control terminal 124, a voltage of 3V is applied to the drain electrode and the source electrode of the field effect transistor 131 constituting the switch element, respectively, A voltage of 1.5V is applied. In addition, a voltage of 1.5 V is applied to the drain electrode and the source electrode of the field effect transistor 132 constituting the switch element, and a voltage of 3 V is applied to the gate electrode.
[0035]
Here, assuming that the threshold values Vth of the field effect transistors 131 and 132 are −0.7 V, in the field effect transistor 131, the gate electrode has a threshold voltage of the field effect transistor 131 from the potential of the source electrode and the drain electrode. The potential is lower than the potential lower by Vth, the impedance between the source electrode and the drain electrode of the field effect transistor 131 is high, and the field effect transistor 131 is in the OFF state. In the field effect transistor 132, the gate electrode has a higher potential than the source electrode and the drain electrode and is 0 V or higher. As a result, the impedance between the source electrode and the drain electrode of the field effect transistor 132 becomes low, and the field effect transistor 132 is in the ON state.
[0036]
In this state, when a high frequency signal is input from the signal input terminal 125, the high frequency signal passes through the low impedance field effect transistor 132 and is output from the signal output terminal 128. Further, the high frequency signal input from the signal input terminal 125 is blocked by the high-impedance field effect transistor 131, and no high frequency signal is output from the signal output terminal 127. As a result, the high frequency signal input from the signal input terminal 125 is output from the signal output terminal 128.
[0037]
According to the circuit configuration of the high frequency switch shown in FIG. 6, the high frequency switch using the MESFET can be controlled by the control voltage value applied to the control terminal 124. At this time, only the positive voltage may be used as the control voltage value.
[0038]
FIG. 7 shows the relationship between the control voltage Vc and the insertion loss between the signal input terminal 125 and the signal output terminals 127 and 128 in the SPDT switch circuit of FIG. Here, in FIG. 7, a state where the insertion loss is about 0 dB is defined as a conduction state, and a state where the insertion loss is −20 dB or less is defined as a cutoff state.
[0039]
In FIG. 7, the control voltage Vc and the reference voltage Vref are Vc. In the region of <Vref− | Vth |, the gate electrode of the field effect transistor 131 is higher than the potentials of the source electrode and the drain electrode, and the field effect transistor 131 is turned on. At this time, the gate electrode of the field effect transistor 132 is at a potential lower than the potential lower than the potential of the field effect transistor 132 by the threshold Vth of the source electrode and the drain electrode. It will be in the OFF state. At this time, the high-frequency signal input from the signal input terminal 125 passes through the field effect transistor 131 and is output from the signal output terminal 127.
[0040]
In the region where the control voltage Vc and the reference voltage Vref are Vc> Vref + | Vth |, the potential of the gate electrode of the field effect transistor 131 is lower than the potential of the source electrode and the drain electrode by the threshold value Vth of the field effect transistor 131. Further, the potential is lower, and the field effect transistor 131 is turned off. At this time, the gate electrode of the field effect transistor 132 is higher than the potentials of the source electrode and the drain electrode, and the field effect transistor 132 is turned on. At this time, the high-frequency signal input from the signal input terminal 125 passes through the field effect transistor 132 and is output from the signal output terminal 128.
[0041]
However, the control voltage Vc is Vref- | Vth | <Vc In the range of <Vref + | Vth |, the insertion loss of the field effect transistor 131 or 132 exists between 0 dB and −20 dB, and the ON / OFF state of the field effect transistor 131 and the field effect transistor 132 of the switch circuit cannot be determined. It becomes. This means that a path between the signal input terminal 125 and the signal output terminal 127 or the signal output terminal 128 of the SPDT switch circuit cannot be selected. That is, there is a range that cannot be set as the voltage of the control voltage Vc for controlling the SPDT switch circuit. This range is described as “indeterminate region” in FIG.
[0042]
For example, when the power supply voltage Vdd is 3 V, the threshold values of the field effect transistors 131 and 132 are −0.7 V, respectively, and the control voltage Vc is in the range from 0 V to 3 V, 0.8 V to 2.2 V The control voltage Vc cannot be set in the range up to (1.4V). Since the range of the control voltage Vc is from 0V to 3V, an area in which the control voltage Vc cannot be set occurs in about a half of the range.
[0043]
Next, a high frequency amplifier circuit corresponding to a plurality of communication methods such as a PDC method and a W-CDMA method will be described. FIG. 8 shows a specific circuit block diagram of the high-frequency amplifier circuit 104 of FIG.
[0044]
In the high frequency amplifier circuit 104, as shown in FIG. 8, a high frequency signal input from a signal input terminal 181 is input to a gain control circuit 183 via an impedance matching circuit 182 that performs impedance conversion, and gain attenuation of the high frequency input signal is performed. Is done. The attenuation amount of the gain control circuit 183 is controlled by setting the voltage value of the control terminal 189. The output signal of the gain control circuit 183 is input to the amplifier 184 and amplified. The output signal of the amplifier 184 is input to the amplifier 186 through the impedance matching circuit 185 that performs impedance conversion and is amplified. The output signal of the amplifier 186 is sent to the signal output terminal 188 via the impedance matching circuit 187 that performs impedance conversion.
[0045]
Next, the use of the high-frequency amplifier circuit 104 of FIG. 8 for a high-frequency circuit block of a communication terminal compatible with a plurality of communication methods will be described. Here, since the frequency used and the output power of the communication terminal are different in the PDC system and the W-CDMA system, it is necessary to determine the circuit configuration of the high-frequency amplifier circuit in accordance with a required system having strict high-frequency characteristics. For example, consider a case where the output power values of the high-frequency amplifier circuit are different. Generally, in a high frequency amplifier circuit, if a large output power is to be obtained, the operating current of the high frequency amplifier circuit increases. For this reason, it is necessary to design a high-frequency amplifier circuit in accordance with a method with large output power.
[0046]
[Patent Document 1]
Japanese Patent No. 30312227
[0047]
[Problems to be solved by the invention]
The first problem is that in the prior art of the high frequency switch, the setting range of the control voltage of the high frequency switch depends on the power supply voltage of the high frequency switch, and the setting range of the control voltage of the high frequency switch is narrow.
[0048]
This is because there is a control voltage range in which the ON / OFF state of the field effect transistor 131 or the field effect transistor 132 constituting the switch circuit cannot be determined. For example, when the power supply voltage Vdd is 3 V, the threshold values of the field effect transistors 131 and 132 are −0.7 V, and the control voltage Vc is 0 V to 3 V, the range is 0.8 V to 2.2 V (1 .4V) cannot set the control voltage Vc. Since the range of the control voltage Vc is 0V to 3V, a region where the control voltage Vc cannot be set occurs in a range of about ½.
[0049]
Here, since the threshold value of the field effect transistor does not depend on the power supply voltage and is substantially constant, when the power supply voltage of the high frequency switch decreases, the power supply voltage of the reference voltage terminal decreases, and the range that can be set as the control voltage is further Narrow.
[0050]
The second problem is that when a high-frequency amplifier circuit corresponding to a plurality of communication methods is configured, the operating current of the high-frequency amplifier circuit increases.
[0051]
The reason is that when the high frequency characteristics such as output power required for the high frequency amplifier circuit differ depending on the communication method, it is necessary to determine the circuit configuration of the high frequency amplifier circuit in accordance with the required high frequency characteristic method. . Therefore, an excessive operating current flows in the operation mode of the communication method with low output power.
[0052]
In particular, in the case of a W-CDMA mobile phone terminal, it is necessary to communicate with a base station continuously during a call, and thus power consumption tends to increase. For this reason, it is preferable to reduce the operating current in the operation mode of the communication method with low output power in order to enable use for a longer time with a battery having a limited capacity. In addition, it is required to realize this without going against the trend of reducing the size and weight.
[0053]
Therefore, an object of the present invention is to provide a high-frequency switch that can expand a setting range of a control voltage.
[0054]
Another object of the present invention is to provide a high-frequency switch / amplifier circuit capable of realizing a reduction in operating current while supporting a plurality of communication methods.
[0055]
Still another object of the present invention is to provide a mobile communication terminal capable of expanding a setting range of a control voltage.
[0056]
Still another object of the present invention is to provide a mobile communication terminal capable of realizing a reduction in operating current while supporting a plurality of communication methods.
[0057]
[Means for Solving the Problems]
According to a first aspect of the present invention, a high frequency switch includes a signal input terminal, first and second signal output terminals, a control terminal to which a control voltage is applied, a changeover switch, and a reference voltage generation circuit. .
[0058]
The change-over switch has one and other signal electrodes and a control electrode, one signal electrode is connected to the signal input terminal, the other signal electrode is connected to the first signal output terminal, and the one and other signals are connected to the control terminal. A first switch element connected to one of the electrodes, one and the other signal electrode, and a control electrode; one signal electrode connected to the signal input terminal; the other signal electrode connected to the second signal output terminal And a second switch element having a control electrode connected to the control terminal.
[0059]
The reference voltage generation circuit generates first and second reference voltages having different values, applies the first reference voltage to the control electrode of the first switch element, and applies the second reference voltage to the second switch element. It has a function to be given to one of the signal electrodes on the other side.
[0060]
The high-frequency switch includes first and second switch elements according to the value of the control voltage based on the relationship between the control voltage and the first reference voltage and the relationship between the control voltage and the second reference voltage. Is selectively conducted.
[0061]
According to this configuration, the signal input to the signal input terminal can be selectively extracted from one of the first and second signal output terminals according to the voltage value applied to the control terminal.
[0062]
In addition, by varying the values of the first and second reference voltages, the conduction state in the second switch element with respect to the control voltage range in the intermediate state between the conduction state and the open state in the first switch element. The control voltage range in the intermediate state between the open state and the open state can be shifted from the conventional control voltage range. As a result, the range of the control voltage in the intermediate state between the conductive state and the open state in the first switch element can be overlapped with the range of the control voltage in the intermediate state between the conductive state and the open state in the second switch element. Therefore, the voltage range of the control voltage for setting the first switch element and the second switch element to the conductive state or the open state can be set wide.
[0063]
A high frequency switch according to a second aspect of the present invention is the high frequency switch according to the first aspect, wherein the first switch element is a first field effect transistor, and one of the source electrode and the drain electrode is one signal electrode, The other of the electrode and the drain electrode becomes the other signal electrode, and the gate electrode becomes the control electrode. The second switch element is composed of a second field effect transistor, and one of the source electrode and the drain electrode serves as one signal electrode, the other of the source electrode and the drain electrode serves as the other signal electrode, and the gate electrode serves as the control electrode. It becomes.
[0064]
According to this configuration, the same function as the high frequency switch according to claim 1 is obtained.
[0065]
A high frequency switch according to a third aspect of the present invention is the high frequency switch according to the second aspect, wherein the second reference voltage is higher than the first reference voltage.
[0066]
According to this configuration, the same function as the high frequency switch according to claim 1 is obtained.
[0067]
A high frequency switch according to a fourth aspect of the present invention is the high frequency switch according to the second aspect, wherein the difference between the first reference voltage and the second reference voltage is substantially the same as the threshold value of the first and second field effect transistors. It is.
[0068]
According to this configuration, in addition to the operation similar to that of the high-frequency switch according to claim 1, the range of the control voltage between the conductive state and the open state of the first field effect transistor, and the second field effect transistor The range of the control voltage in the intermediate state between the conductive state and the open state can be almost completely overlapped. Therefore, the voltage range of the control voltage for setting the first field effect transistor and the second field effect transistor to the conductive state or the open state can be set as wide as possible.
[0069]
A high frequency switch according to a fifth aspect of the present invention is the high frequency switch according to the second aspect, wherein the reference voltage generating circuit is formed of a series circuit of three or more resistors.
[0070]
According to this configuration, the circuit voltage can be reduced because the reference voltage generation circuit can be simply formed in addition to the same operation as the high-frequency switch according to the first aspect.
[0071]
A high frequency switch according to a sixth aspect of the present invention is the high frequency switch according to the second aspect, wherein the field effect transistor includes a source electrode, a drain electrode, and at least one gate electrode, and the gap between the source electrode and the drain electrode. The gate electrode is disposed on the gate electrode, and the gate electrode and the control terminal or the output terminal of the reference voltage generation circuit are connected via a resistor.
[0072]
According to this configuration, in addition to the operation similar to that of the first aspect, when the number of gate electrodes is two or more, the distortion with respect to the signal level input to the field effect transistor without increasing the gate width of the field effect transistor. The characteristics can be improved.
[0073]
A high-frequency switch / amplifier circuit according to a seventh aspect of the invention includes a signal input terminal, first and second signal output terminals, a control terminal to which a control voltage is applied, a changeover switch, a first amplifier, A second amplifier and a reference voltage generation circuit are provided.
[0074]
The changeover switch includes a first switch element having one and other signal electrodes and a control electrode, one signal electrode connected to the signal input terminal, and one of the other signal electrodes connected to the control terminal. And a second switch element having one and other signal electrodes and a control electrode, one signal electrode connected to the signal input terminal, and a control electrode connected to the control terminal.
[0075]
The first amplifier has an input terminal connected to the other signal electrode of the first switch element and an output terminal connected to the first signal output terminal.
[0076]
The second amplifier has an input terminal connected to the other signal electrode of the second switch element and an output terminal connected to the second signal output terminal.
[0077]
The reference voltage generation circuit generates first and second reference voltages, applies the first reference voltage to the control electrode of the first switch element, and applies the second reference voltage to one and the other of the second switch elements. It has a function to give to any of the signal electrodes.
[0078]
The high-frequency switch / amplifier circuit includes first and second control circuits according to the value of the control voltage based on the relationship between the control voltage and the first reference voltage and the relationship between the control voltage and the second reference voltage. The switch element is selectively turned on. In addition, when the first switch element is conductive, the first amplifier is in an operating state, the second amplifier is inactive, and when the second switch element is conductive, the first amplifier is inactive. 2 amplifiers are put into operation.
[0079]
According to this configuration, the signal input to the signal input terminal can be selectively extracted from either one of the first and second signal output terminals as an amplified signal according to the voltage value applied to the control terminal. It becomes.
[0080]
Further, since the first amplifier and the second amplifier are connected via the changeover switch, the amplifier can be configured corresponding to a plurality of communication systems (for example, the PDC system and the W-CDMA system). The amplifier can be designed according to the communication method. Therefore, designing with an optimum circuit scale can be performed, and an increase in circuit scale and an increase in operating current can be prevented.
[0081]
The high-frequency switch / amplifier circuit according to an eighth aspect of the present invention is the high-frequency switch / amplifier circuit according to the seventh aspect, wherein the first switch element is a first field effect transistor, and one of the source electrode and the drain electrode is one of them. The other of the source electrode and the drain electrode is the other signal electrode, and the gate electrode is the control electrode. The second switch element includes a second field effect transistor, and one of the source electrode and the drain electrode serves as one signal electrode, the other of the source electrode and the drain electrode serves as the other signal electrode, and the gate electrode serves as the control electrode. . The first amplifier is composed of a third field effect transistor. The gate electrode serves as an input terminal, the drain electrode serves as an output terminal, and the source electrode is grounded at a high frequency. The second amplifier is composed of a fourth field effect transistor, with the gate electrode serving as the input terminal, the drain electrode serving as the output terminal, and the source electrode grounded at a high frequency.
[0082]
According to this configuration, in addition to the same operation as the high-frequency switch / amplifier circuit according to claim 7, the conduction state of the first field-effect transistor can be changed by making the values of the first and second reference voltages different from each other. The control voltage range in the intermediate state between the conduction state and the open state in the second field effect transistor can be shifted from the control voltage range in the conventional example with respect to the control voltage range in the intermediate state between the open state and the open state. . As a result, the range of the control voltage in the intermediate state between the conductive state and the open state in the first field effect transistor may overlap the range of the control voltage in the intermediate state between the conductive state and the open state in the second field effect transistor. it can. Therefore, the voltage range of the control voltage for setting the first field effect transistor and the second field effect transistor to the conductive state or the open state can be set wide.
[0083]
The high-frequency switch / amplifier circuit according to a ninth aspect of the present invention is the high-frequency switch / amplifier circuit according to the eighth aspect, wherein the second reference voltage is higher than the first reference voltage.
[0084]
According to this configuration, the same function as the high frequency switch / amplifier circuit according to the seventh aspect is obtained.
[0085]
A high frequency switch / amplifier circuit according to a tenth aspect of the present invention is the high frequency switch / amplifier circuit according to the eighth aspect, wherein the difference between the first reference voltage and the second reference voltage is that of the first and second field effect transistors. It is almost the same as the threshold value.
[0086]
According to this configuration, in addition to the same operation as the high-frequency switch / amplifier circuit according to claim 7, the range of the control voltage in the intermediate state between the conduction state and the open state in the first field effect transistor, and the second electric field The conduction state of the effect transistor and the range of the control voltage in the intermediate state of the open state can be almost completely overlapped. Therefore, the voltage range of the control voltage for setting the first field effect transistor and the second field effect transistor to the conductive state or the open state can be set as wide as possible.
[0087]
The high-frequency switch / amplifier circuit according to an eleventh aspect of the present invention is the high-frequency switch / amplifier circuit according to the eighth aspect, wherein the reference voltage generation circuit is constituted by a series circuit of three or more resistors.
[0088]
According to this configuration, the circuit voltage can be reduced because the reference voltage generation circuit can be simply formed in addition to the same operation as the high frequency switch / amplifier circuit according to the seventh aspect.
[0089]
A high-frequency switch / amplifier circuit according to a twelfth aspect of the present invention is the high-frequency switch / amplifier circuit according to the seventh aspect, wherein the control terminal and one of the power terminals of the first and second amplifiers are connected in common. .
[0090]
According to this configuration, the number of terminals can be reduced because it has the same function as the high frequency switch / amplifier circuit according to the seventh aspect and it is not necessary to provide a separate control terminal for the changeover switch. Furthermore, since the control of the operation / stop of the amplifier and the path selection control of the changeover switch can be realized by one terminal, the control becomes easy.
[0091]
A high-frequency switch / amplifier circuit according to a thirteenth aspect of the present invention is the high-frequency switch / amplifier circuit according to the seventh aspect, further comprising a third amplifier having an output terminal connected to a signal input terminal, and an input of the third amplifier The signal input to the terminal is amplified and input to the signal input terminal, and the power supply terminal of the third amplifier is connected in common with the power supply terminal of the reference voltage generation circuit.
[0092]
According to this configuration, in addition to the same operation as the high-frequency switch / amplifier circuit according to the seventh aspect, by providing the third amplifier, the gain as a whole can be increased. In addition, since it is not necessary to provide a separate power supply terminal for the reference voltage generation circuit, the number of terminals can be reduced.
[0093]
A high-frequency switch / amplifier circuit according to a fourteenth aspect of the invention includes a signal input terminal, first and second signal output terminals, a control terminal to which a control voltage is applied, a changeover switch, a reference voltage generation circuit, And an amplifier having an output terminal connected to the signal input terminal.
[0094]
The change-over switch has one and other signal electrodes and a control electrode, one signal electrode is connected to the signal input terminal, the other signal electrode is connected to the first signal output terminal, and the one and other signals are connected to the control terminal. A first switch element connected to one of the electrodes, one and the other signal electrode, and a control electrode; one signal electrode connected to the signal input terminal; the other signal electrode connected to the second signal output terminal And a second switch element having a control electrode connected to the control terminal.
[0095]
The reference voltage generation circuit generates first and second reference voltages having different values, applies the first reference voltage to the control electrode of the first switch element, and applies the second reference voltage to the second switch element. One is applied to the other signal electrode.
[0096]
Then, based on the relationship between the control voltage and the first reference voltage and the relationship between the control voltage and the second reference voltage, the first and second switch elements are selectively turned on according to the value of the control voltage. Let's make it. Further, the signal input to the input terminal of the amplifier is amplified and input to the signal input terminal, and the power supply terminal of the amplifier is shared with the power supply voltage of the reference voltage generation circuit.
[0097]
According to this configuration, the signal input to the signal input terminal can be selectively extracted from either one of the first and second signal output terminals as an amplified signal according to the voltage value applied to the control terminal. It becomes.
[0098]
Moreover, the gain can be increased as a whole by providing the amplifier. In addition, since it is not necessary to provide a separate power supply terminal for the reference voltage generation circuit, the number of terminals can be reduced.
[0099]
A mobile communication terminal according to a fifteenth aspect of the present invention is a mobile communication terminal having a high-frequency switch having a high-frequency signal path selection function, wherein the high-frequency switch has a signal input terminal, and first and second signal outputs. A terminal, a control terminal to which a control voltage is applied, a changeover switch, and a reference voltage generation circuit.
[0100]
The change-over switch has one and other signal electrodes and a control electrode, one signal electrode is connected to the signal input terminal, the other signal electrode is connected to the first signal output terminal, and the one and other signals are connected to the control terminal. A first switch element connected to one of the electrodes, one and the other signal electrode, and a control electrode; one signal electrode connected to the signal input terminal; the other signal electrode connected to the second signal output terminal And a second switch element having a control electrode connected to the control terminal.
[0101]
The reference voltage generation circuit generates first and second reference voltages having different values, applies the first reference voltage to the control electrode of the first switch element, and applies the second reference voltage to the second switch element. It has a function to be given to one of the signal electrodes on the other side.
[0102]
Then, the high frequency switch switches the first and second switch elements according to the value of the control voltage based on the relationship between the control voltage and the first reference voltage and the relationship between the control voltage and the second reference voltage. It is made to conduct selectively.
[0103]
According to this configuration, the same function as the high frequency switch according to claim 1 is obtained.
[0104]
A mobile communication terminal according to a sixteenth aspect of the present invention is a mobile communication terminal having a high-frequency switch / amplifier circuit having a high-frequency signal path selection function, wherein the high-frequency switch / amplifier circuit includes a signal input terminal, And a second signal output terminal, a control terminal to which a control voltage is applied, a changeover switch, a first amplifier, a second amplifier, and a reference voltage generation circuit.
[0105]
The changeover switch includes a first switch element having one and other signal electrodes and a control electrode, one signal electrode connected to the signal input terminal, and one of the other signal electrodes connected to the control terminal. And a second switch element having one and other signal electrodes and a control electrode, one signal electrode connected to the signal input terminal, and a control electrode connected to the control terminal.
[0106]
The first amplifier has an input terminal connected to the other signal electrode of the first switch element and an output terminal connected to the first signal output terminal.
[0107]
The second amplifier has an input terminal connected to the other signal electrode of the second switch element and an output terminal connected to the second signal output terminal.
[0108]
The reference voltage generation circuit generates first and second reference voltages, applies the first reference voltage to the control electrode of the first switch element, and applies the second reference voltage to one and the other of the second switch elements. It has a function to give to any of the signal electrodes.
[0109]
The high-frequency switch / amplifier circuit includes first and second control circuits according to the value of the control voltage based on the relationship between the control voltage and the first reference voltage and the relationship between the control voltage and the second reference voltage. The switch element is selectively turned on. In addition, when the first switch element is conductive, the first amplifier is in an operating state, the second amplifier is inactive, and when the second switch element is conductive, the first amplifier is inactive. 2 amplifiers are put into operation.
[0110]
According to this configuration, the same function as the high frequency switch / amplifier circuit according to the seventh aspect is obtained.
[0111]
A mobile communication terminal according to a seventeenth aspect of the present invention is a mobile communication terminal having a high-frequency switch / amplifier circuit having a high-frequency signal path selection function, wherein the high-frequency switch / amplifier circuit includes: a signal input terminal; 1 and a second signal output terminal, a control terminal to which a control voltage is applied, a changeover switch, a reference voltage generation circuit, and an amplifier having an output terminal connected to the signal input terminal.
[0112]
The change-over switch has one and other signal electrodes and a control electrode, one signal electrode is connected to the signal input terminal, the other signal electrode is connected to the first signal output terminal, and the one and other signals are connected to the control terminal. A first switch element connected to one of the electrodes, one and the other signal electrode, and a control electrode; one signal electrode connected to the signal input terminal; the other signal electrode connected to the second signal output terminal And a second switch element having a control electrode connected to the control terminal.
[0113]
The reference voltage generation circuit generates first and second reference voltages having different values, applies the first reference voltage to the control electrode of the first switch element, and applies the second reference voltage to the second switch element. One is applied to the other signal electrode.
[0114]
Then, based on the relationship between the control voltage and the first reference voltage and the relationship between the control voltage and the second reference voltage, the first and second switch elements are selectively turned on according to the value of the control voltage. I try to let them. Further, the signal input to the input terminal of the amplifier is amplified and input to the signal input terminal, and the power supply terminal of the amplifier is made common with the power supply voltage of the reference voltage generation circuit.
[0115]
According to this configuration, the same function as the high-frequency switch / amplifier circuit according to the fourteenth aspect is obtained.
[0116]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a high-frequency amplifier circuit according to an embodiment of the present invention and a mobile phone terminal using the same will be described with reference to the drawings.
[0117]
[First Embodiment]
FIG. 1 is a block diagram showing a configuration of a high-frequency amplifier circuit according to the first embodiment of the present invention. The high-frequency switch in FIG. 1 is an SPDT switch circuit and corresponds to the high-frequency switch 203 in the block diagram of the transmission unit of the conventional mobile phone terminal shown in FIG. That is, in the mobile phone terminal according to the embodiment of the present invention, the high-frequency switch shown in FIG. 1 is used in place of the high-frequency switch 203 in the transmission unit of the conventional mobile phone terminal shown in FIG.
[0118]
Hereinafter, the high frequency switch of FIG. 1 will be described in detail.
[0119]
In FIG. 1, a source electrode of a field effect transistor 219 that is a switching element is connected to a signal input terminal 215 via a capacitor 230, and a drain electrode of the field effect transistor 219 is connected to a signal output terminal 216 via a capacitor 231. Yes. Further, the source electrode of the field effect transistor 220 which is a switch element is connected to the signal input terminal 215 via the capacitor 232, and the drain electrode of the field effect transistor 220 is connected to the signal output terminal 217 via the capacitor 233. Note that since the source electrode and the drain electrode of the field effect transistors 219 and 220 are structurally the same, the connection may be reversed.
[0120]
A source electrode of the field effect transistor 219 is connected to the control terminal 218 via the resistor 221. Further, the gate electrode of the field effect transistor 220 is connected to the control terminal 218 via the resistor 228.
[0121]
The source electrode and the drain electrode of the field effect transistor 219 are connected to each other through the resistor 222 and have the same potential. Further, the source electrode and the drain electrode of the field effect transistor 220 are connected to each other via the resistor 227 and have the same potential.
[0122]
A series circuit of resistors 224, 225, and 226 is connected between the power supply terminal 211 and the ground terminal 212. Two connection points of the series circuit of resistors 224, 225, and 226 are the reference voltage terminal 213 and the reference voltage terminal 214, respectively. It has become. The gate electrode of the field effect transistor 219 is connected to the reference voltage terminal 214 via the resistor 223. Further, the source electrode of the field effect transistor 220 is connected to the reference voltage terminal 213 through the resistor 229.
[0123]
The reference voltage generation circuit is configured by a series circuit of resistors 224, 225, and 226 connected between the power supply terminal 211 and the ground terminal 212. Capacitors 230 to 233 are inserted to remove direct current components. The resistors 221, 222, 223, 227, 228, and 229 have high resistance values. The control terminal (Vc) 218 is a terminal for controlling the operating state of the switch circuit.
[0124]
Next, the operation of the high frequency switch in the circuit of FIG. 1 will be briefly described. By setting the relationship between the control voltage Vc applied to the control terminal 218 and the reference voltage Vref1 obtained from the reference voltage generation circuit and the reference voltage Vref2 to a predetermined state, the field effect transistors 219 and 220 are selectively turned on, Or let it open.
[0125]
Specifically, the source and drain electrodes of the field effect transistors 219 and 220 are set in a conductive state or in an open state. Thus, switching between the signal input terminal 215 and the signal output terminals 216 and 217 is realized.
[0126]
Here, the resistor 221, the resistor 222, the resistor 223, the resistor 227, the resistor 228, and the resistor 229 have high resistance values, and the voltage drop between both terminals of the resistors 221 to 223 and 227 to 229 is almost the same. Make it not exist. The potential of each terminal and electrode is as follows. That is, the control terminal 218 to which the control voltage Vc is applied, the gate electrode of the field effect transistor 220, and the source electrode and drain electrode of the field effect transistor 219 have the same potential. Further, the reference voltage terminal 213 and the source electrode and drain electrode of the field effect transistor 220 have the same potential. The reference voltage terminal 214 and the gate electrode of the field effect transistor 219 are at the same potential.
[0127]
When the switching operation is performed in the circuit of FIG. 1, if the control voltage applied to the control terminal 218 is Vc, the reference voltage appearing at the reference voltage terminal 213 is Vref1, and the reference voltage appearing at the reference voltage terminal 214 is Vref2, then the field effect transistor 219 and the conduction / opening relationship between the source electrode and the drain electrode of the field effect transistor 220 are as follows.
In the case of the field effect transistor 219
Vc <Vref2 Between source electrode and drain electrode: conduction
Vc> Vref2 + | Vth | Between source electrode and drain electrode: open
In the case of the field effect transistor 220
Vc> Vref1 Between source electrode and drain electrode: conduction
Vc <Vref1 − | Vth | Between source electrode and drain electrode: Open
However, the threshold value of the field effect transistor 219 and the field effect transistor 220 is a voltage Vth.
[0128]
The control voltage Vc is relative to the reference voltage Vref2.
Vref2 <Vc <Vref2 + | Vth |
When the relationship is, the field electrode transistor 219 has an intermediate state between conduction and open between the source electrode and the drain electrode.
[0129]
Also, the control voltage Vc is relative to the reference voltage Vref1.
Vref1 ― | Vth | <Vc <Vref1
When the relationship is established, the source electrode and the drain electrode of the field effect transistor 220 are in an intermediate state between conduction and open.
[0130]
Such a control voltage range cannot be set as a voltage value for controlling the switch. Here, in order to expand the operation range of the switch circuit, it is considered that the control voltage range in which the source electrode and the drain electrode of the field effect transistor 219 and the field effect transistor 220 are in an intermediate state between conduction and open is overlapped.
[0131]
At this time, the relationship between the reference voltages Vref1 and Vref2 is as follows.
[0132]
Vref2 = Vref1-| Vth | ――― (1)
When the upper limit value of the control voltage Vc is equal to the power supply voltage Vdd of the switch circuit, the power supply voltage Vdd and the reference voltage Vref1 are set to equalize the range of the control voltage Vc in which the field effect transistor 219 and the field effect transistor 220 become conductive. , Vref2 is as follows.
[0133]
Vdd = (Vref1 + Vref2) ――― (2)
From the equations (1) and (2), the relationship among the reference voltages Vref1, Vref2, the power supply voltage Vdd, and the threshold value Vth of the field effect transistor is as follows.
[0134]
Vref1 = 0.5 × Vdd + 0.5 × | Vth |
Vref2 = 0.5 × Vdd ― 0.5 × | Vth |
Next, the operation of the switch circuit of FIG. 1 will be described. As an example, consider a case where the power supply voltage Vdd is 3 V, the upper limit value of the control voltage Vc is 3 V, and the threshold values Vth of the field effect transistor 219 and the field effect transistor 220 are −0.7 V. At this time, the voltage values of the reference voltage Vref1 and the reference voltage Vref2 are 1.15V and 1.85V, respectively.
[0135]
The voltage values of the reference voltage Vref1 and the reference voltage Vref2 are not limited to the above values. For example, if the reference voltage Vref1 is within the range of 1.15V ± 0.34V, the control voltage range can be widened compared to the conventional example. Similarly, if the reference voltage Vref2 is within the range of 1.85 V ± 0.34 V, the control voltage range can be widened compared to the conventional example. In addition, the control voltage range of a prior art example is 0V-0.8V, 2.2V-3V.
[0136]
Also, the threshold value of the field effect transistor is not limited to -0.7 V, and the two field effect transistors need not have the same threshold value.
[0137]
FIG. 2 shows the relationship between the control voltage Vc and the insertion loss between the signal input terminal 215 and the signal output terminals 216 and 217 of the high frequency switch of FIG. Here, in FIG. 2, a state where the insertion loss is about 0 dB is defined as a conduction state, and a state where the insertion loss is −20 dB or less is defined as a cutoff state.
[0138]
In FIG. 2, the control voltage Vc is Vc. In the region of <0.5 × (Vdd− | Vth |), the gate electrode of the field effect transistor 219 is higher in potential than the source electrode and the drain electrode, and the source electrode and the drain electrode of the field effect transistor 219 are electrically connected. It is in a state. The gate electrode of the field effect transistor 220 is further lower than the potential lower than the potential of the source electrode and the drain electrode by the threshold value Vth of the field effect transistor 220. At this time, the high-frequency signal input from the signal input terminal 215 passes through the field effect transistor 219 and is output from the signal output terminal 216.
[0139]
In the region where the control voltage Vc is Vc> 0.5 × (Vdd + | Vth |), the potential of the gate electrode of the field effect transistor 219 is lower than the potential of the source electrode and the drain electrode by the threshold value Vth of the field effect transistor 219. Further, the potential is further lower, and the source electrode and the drain electrode of the field effect transistor 219 are open. Further, the gate electrode of the field effect transistor 220 is at a higher potential than the source electrode and the drain electrode thereof, and the source electrode and the drain electrode of the field effect transistor 220 are in a conductive state. At this time, the high-frequency signal input from the signal input terminal 215 passes through the field effect transistor 220 and is output from the signal output terminal 217.
[0140]
Control voltage Vc is 0.5 × (Vdd- | Vth |) <Vc In the range of <0.5 × (Vdd + | Vth |), the insertion loss of the field effect transistor 219 or the field effect transistor 220 exists between 0 dB and −20 dB, and the source of the field effect transistor 219 and the field effect transistor 220 of the switch circuit Between the electrode and the drain electrode is an intermediate state between conduction and open. In this case, a path between the signal input terminal 215 and the signal output terminal 216 or the signal output terminal 217 of the high frequency switch cannot be selected. The range of the control voltage Vc at that time is 1.15V to 1.85V (0.7V).
[0141]
In the circuit of FIG. 1, switching of the high frequency switch is realized by the control voltage Vc, and by providing two kinds of reference voltages used in the field effect transistor of the high frequency switch, the setting range of the control voltage can be expanded.
[0142]
In the circuit of FIG. 1, single-gate field effect transistors are used as the field effect transistors 219 and 220. However, as shown in FIG. 9, a plurality of (two or more) field effect transistors are provided between the source electrode and the drain electrode. A structure using a multi-gate field effect transistor having a structure in which a gate electrode is arranged may be used. In FIG. 9, reference numerals 219A and 220A denote multi-gate field effect transistors, respectively, and reference numerals 223A and 223B denote resistors connected between the two gate electrodes of the multi-gate field effect transistor 219A and the reference voltage terminal 214, respectively. Reference numerals 228A and 228B denote resistors connected between the two gate electrodes of the multi-gate field effect transistor 220A and the control terminal 218. Other configurations are the same as those in FIG.
[0143]
As described above, by using the multi-gate field effect transistor, the gate width of the multi-gate field effect transistors 219A and 220A is not increased as compared with the gate width of the single-gate type field effect transistors 219 and 220. The distortion characteristic with respect to the signal level input to the field effect transistor can be improved.
[0144]
In the multi-gate field effect transistors 219A and 220A, a plurality of gate electrodes arranged between the source electrode and the drain electrode and the control terminal 218 or the reference voltage terminal 211 are respectively connected via resistors 223A, 223B, 228A, and 228B. With the connected structure, the isolation of the gate electrode can be improved. Therefore, a high frequency switch can be configured without deteriorating high frequency characteristics.
[0145]
[Second Embodiment]
FIG. 3 is a block diagram showing a configuration of a high-frequency circuit including a high-frequency switch / amplifier circuit according to the second embodiment of the present invention. The high frequency switch / amplifier circuit of FIG. 3 corresponds to the high frequency amplifier circuit 104 and the high frequency switch 105 in the block diagram of the transmission unit of the conventional mobile phone terminal shown in FIG. In the mobile phone terminal according to the embodiment of the present invention, the high-frequency switch / amplifier circuit of FIG. 3 is used instead of the high-frequency amplifier circuit 202 and the high-frequency switch 203 in the transmission unit 200 of the conventional mobile phone terminal shown in FIG. Is used.
[0146]
Hereinafter, the high-frequency switch / amplifier circuit of FIG. 3 will be described in detail.
[0147]
In FIG. 3, the high frequency signal input from the signal input terminal 240 is input to the gain control circuit 242 via the impedance matching circuit 241 that performs impedance conversion, and gain attenuation of the high frequency input signal is performed. The attenuation amount of the gain control circuit 242 is controlled by setting the voltage value of the control terminal 243. The output signal of the gain control circuit 242 is input to the amplifier 244 and amplified. The output signal of the amplifier 244 is input to the common terminal 245a of the high frequency switch 245.
[0148]
The signal output from the terminal 245c of the high-frequency switch 245 is input to the amplifier 247 via the impedance matching circuit 246 that performs impedance conversion and is amplified. The output signal of the amplifier 247 is sent to the signal output terminal 249 via the impedance matching circuit 248 that performs impedance conversion.
[0149]
The signal output from the terminal 245b of the high frequency switch 245 is input to the amplifier 251 through the impedance matching circuit 250 that performs impedance conversion, and is amplified. The output signal of the amplifier 251 is sent to the signal output terminal 253 via the impedance matching circuit 252 that performs impedance conversion.
[0150]
The power supply voltage terminal 254 is connected to the reference voltage terminal 242 b of the gain control circuit 242, the power supply terminal of the amplifier 244, and the power supply terminal 245 d of the high frequency switch 245. The power supply voltage terminal 255 is connected to the control terminal 245e of the high frequency switch 245 and the power supply terminal of the amplifier 247. The power supply terminal 256 is connected to the power supply terminal of the amplifier 251.
[0151]
The amplifiers 244, 247, and 251 described above include, for example, a field effect transistor 261, a coil 262, capacitors 263 to 265, and resistors 266 and 267, as shown in FIG. An input terminal 268 is connected to the gate electrode via a capacitor 263, an output terminal 269 is connected to the drain electrode via a capacitor 264, and the source electrode is grounded in high frequency.
[0152]
Note that, as the amplifiers 244, 247, and 251, bipolar transistors can be used instead of the field effect transistors. In that case, the collector electrode, base electrode, and emitter electrode of the bipolar transistor correspond to the drain electrode, gate electrode, and source electrode of the field effect transistor, respectively. Specifically, for example, as shown in FIG. 11, it is composed of a bipolar transistor 271, a coil 272, capacitors 273, 274, and resistors 275, 276. An input terminal 277 is connected to the base electrode via a capacitor 273, an output terminal 278 is connected to the collector electrode via a capacitor 274, and the emitter electrode is grounded.
[0153]
As an amplifier, a bipolar transistor can be used instead of a field effect transistor. In that case, the collector electrode, base electrode, and emitter electrode of the bipolar transistor correspond to the drain electrode, gate electrode, and source electrode of the field effect transistor, respectively.
[0154]
Next, the operation of the high frequency switch / amplifier circuit of FIG. 3 will be briefly described. Further, the high frequency switch 245 includes the high frequency switch shown in FIG. 1, and the terminals of the high frequency switch 245 correspond to the high frequency switch of FIG. 1 as follows. The common terminal 245a of the high frequency switch 245 corresponds to the signal input terminal 215, the terminal 245b corresponds to the signal output terminal 216, the terminal 245c corresponds to the signal output terminal 217, and the power terminal 245d corresponds to the power terminal 211. The control terminal 245e corresponds to the control terminal 218.
[0155]
As an example, consider a case where a voltage of 3V is applied to the power supply terminal 254, a voltage of 3V is applied to the power supply terminal 255, and the power supply terminal 256 is set to 0V. At this time, the amplifier 244 is in an ON (operation) state, the amplifier 247 is in an ON (operation) state, and the amplifier 251 is in an OFF (non-operation) state. The high frequency switch 245 is in a state where the common terminal 245a and the terminal 245c are connected. At this time, the high frequency signal input to the signal input terminal 240 of the high frequency circuit of FIG. 3 is amplified by the amplifier 244 and the amplifier 247 and output from the signal output terminal 249.
[0156]
Next, consider a case where a voltage of 3V is applied to the power supply terminal 254, the power supply terminal 255 is set to 0V, and a voltage of 3V is applied to the power supply terminal 256. At this time, the amplifier 244 is in an ON (operation) state, the amplifier 247 is in an OFF (non-operation) state, and the amplifier 251 is in an ON (operation) state. The high frequency switch 245 is in a state where the common terminal 245a and the terminal 245b are connected. At this time, the signal input to the signal input terminal 240 of the high frequency amplifier circuit is amplified by the amplifier 244 and the amplifier 251 and output from the signal output terminal 253.
[0157]
Here, by configuring the amplifier 247 and the amplifier 251 in accordance with the specifications in the PDC method and the W-CDMA method, it is possible to set an optimum operating current value for each specification.
[0158]
Further, by making the control voltage 245e of the high frequency switch 245 and the power supply terminal 255 of the amplifier 247 common, the number of terminals can be reduced, the selection of the switch path and the selection of the amplifier circuit can be performed simultaneously, and the control of the high frequency amplifier circuit can be performed. It can be simplified.
[0159]
As described above, according to the high frequency switch of the embodiment of the present invention, the changeover switch is configured by the two field effect transistors 219 and 220, and the two reference voltage terminals 213 and 213 having different voltage values are provided in the reference voltage generation circuit. 214 is provided. One reference voltage terminal 213 generates a value obtained by adding a voltage value that is 1/2 of the absolute value of the threshold value of the field effect transistors 219 and 220 to the intermediate value of the power supply voltage. Apply to electrode. The other reference voltage terminal 214 generates a value obtained by subtracting a voltage value that is 1/2 of the absolute value of the threshold value of the field effect transistors 219 and 220 from the intermediate value of the power supply voltage. Apply to. Thus, the voltage range in which the field effect transistors 219 and 220 are in an intermediate state between on and off can be overlapped, so that the control voltage setting range for turning on and off the field effect transistors 219 and 220 can be widened. it can.
[0160]
Further, according to the high frequency switch / amplifier circuit of the embodiment of the present invention, the high frequency switch for selecting the first amplifier 247 and the second amplifier 248 is provided, and the first and the first corresponding to the communication system to be used are provided. A configuration in which one of the two amplifiers 247 and 248 is selected is employed. As a result, amplifier circuit configurations corresponding to the specifications of the respective communication systems can be realized, so that the amplifier circuit design can be brought into an optimum state, and the operating current can be reduced.
[0161]
Further, by making the control voltage of the high frequency switch 245 and the power supply voltage of the amplifier 247 common, the number of terminals can be reduced, and the control of the high frequency switch / amplifier circuit can be simplified.
[0162]
Further, by making the power supply voltage of the third amplifier 244 and the power supply voltage of the reference voltage generation circuit in the high frequency switch 245 common, the number of terminals can be reduced.
[0163]
【The invention's effect】
According to the high frequency switch of the first aspect of the present invention, the range of the control voltage in the intermediate state between the conductive state and the open state in the first switch element is obtained by making the values of the first and second reference voltages different. On the other hand, the control voltage range in the intermediate state between the conductive state and the open state in the second switch element can be shifted from the control voltage range of the conventional example. As a result, the range of the control voltage in the intermediate state between the conductive state and the open state in the first switch element can be overlapped with the range of the control voltage in the intermediate state between the conductive state and the open state in the second switch element. Therefore, the voltage range of the control voltage for setting the first switch element and the second switch element to the conductive state or the open state can be set wide.
[0164]
According to the high frequency switch of claim 2 of the present invention, the same effect as the high frequency switch of claim 1 is obtained.
[0165]
According to the high frequency switch of the present invention, the same effect as the high frequency switch of the first aspect can be obtained.
[0166]
According to the high frequency switch of the present invention, in addition to the same effect as the high frequency switch of the first aspect, the range of the control voltage in the intermediate state between the conductive state and the open state in the first field effect transistor is Thus, it is possible to almost completely overlap the range of the control voltage in the intermediate state between the conductive state and the open state in the second field effect transistor. Therefore, the voltage range of the control voltage for setting the first field effect transistor and the second field effect transistor to the conductive state or the open state can be set as wide as possible.
[0167]
According to the high frequency switch described in claim 5 of the present invention, the same effect as the high frequency switch described in claim 1 can be obtained, and the reference voltage generating circuit can be simply formed, so that the circuit scale can be reduced.
[0168]
According to the high frequency switch of claim 6 of the present invention, the same effect as the high frequency switch of claim 1 can be obtained, and when the number of gate electrodes is two or more, the gate width of the field effect transistor is increased. In addition, the distortion characteristics with respect to the signal level input to the field effect transistor can be improved.
[0169]
According to the high frequency switch / amplifier circuit of the present invention, since the first amplifier and the second amplifier are connected via the changeover switch, a plurality of communication systems (for example, PDC system and W -CDMA) can be configured, and the amplifier can be designed according to the communication system. Therefore, designing with an optimum circuit scale can be performed, and an increase in circuit scale and an increase in operating current can be prevented.
[0170]
According to the high frequency switch / amplifier circuit described in claim 8 of the present invention, the same effect as that of the high frequency switch / amplifier circuit described in claim 7 can be obtained, and the first and second reference voltages can be made different. The conventional control voltage range of the intermediate state between the conduction state and the open state of the second field effect transistor is compared to the range of the control voltage of the intermediate state between the conduction state and the open state of the first field effect transistor. Can be shifted from the control voltage range. As a result, the range of the control voltage in the intermediate state between the conductive state and the open state in the first field effect transistor may overlap the range of the control voltage in the intermediate state between the conductive state and the open state in the second field effect transistor. it can. Therefore, the voltage range of the control voltage for setting the first field effect transistor and the second field effect transistor to the conductive state or the open state can be set wide.
[0171]
According to the high frequency switch / amplifier circuit of the ninth aspect of the present invention, the same effect as that of the high frequency switch / amplifier circuit according to the seventh aspect is obtained.
[0172]
According to the high frequency switch / amplifier circuit of claim 10 of the present invention, the same effect as that of the high frequency switch / amplifier circuit according to claim 7 can be obtained, and an intermediate state between the conductive state and the open state of the first field effect transistor. And the range of the control voltage in the intermediate state between the conductive state and the open state in the second field effect transistor can be almost completely overlapped. Therefore, the voltage range of the control voltage for setting the first field effect transistor and the second field effect transistor to the conductive state or the open state can be set as wide as possible.
[0173]
According to the high frequency switch / amplifier circuit according to claim 11 of the present invention, the same effect as the high frequency switch / amplifier circuit according to claim 7 can be obtained, and the reference voltage generation circuit can be simply formed, so that the circuit scale can be reduced. can do.
[0174]
According to the high frequency switch / amplifier circuit of the twelfth aspect of the present invention, the same effect as that of the high frequency switch / amplifier circuit according to the seventh aspect is obtained, and it is not necessary to provide a separate control terminal for the changeover switch. Can be reduced. Furthermore, since the control of the operation / stop of the amplifier and the path selection control of the changeover switch can be realized by one terminal, the control becomes easy.
[0175]
According to the high frequency switch / amplifier circuit of the thirteenth aspect of the present invention, the same effect as that of the high frequency switch / amplifier circuit according to the seventh aspect is obtained, and the gain is increased as a whole by providing the third amplifier. Can be made. In addition, since it is not necessary to provide a separate power supply terminal for the reference voltage generation circuit, the number of terminals can be reduced.
[0176]
According to the high frequency switch / amplifier circuit of the fourteenth aspect of the present invention, the same effect as that of the high frequency switch / amplifier circuit according to the seventh aspect can be obtained, and the gain can be increased as a whole by providing the amplifier. it can. In addition, since it is not necessary to provide a separate power supply terminal for the reference voltage generation circuit, the number of terminals can be reduced.
[0177]
According to the mobile communication terminal of the fifteenth aspect of the present invention, the same effect as the high-frequency switch of the first aspect can be obtained.
[0178]
According to the mobile communication terminal of the sixteenth aspect of the present invention, the same effect as that of the high frequency switch / amplifier circuit of the seventh aspect is obtained.
[0179]
According to the mobile communication terminal of the seventeenth aspect of the present invention, the same effect as the high-frequency switch / amplifier circuit of the fourteenth aspect is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a high frequency switch according to a first embodiment of the present invention.
FIG. 2 is a graph showing a state of a changeover switch in the high frequency switch according to the first embodiment of the present invention.
FIG. 3 is a block diagram showing a configuration of a high-frequency switch / amplifier circuit according to a second embodiment of the present invention.
FIG. 4 is a block diagram showing a configuration of a radio unit of a conventional mobile phone terminal.
FIG. 5 is a block diagram showing a configuration of a radio unit of another conventional mobile phone terminal.
FIG. 6 is a block diagram showing a configuration of a conventional high-frequency switch.
FIG. 7 is a graph showing a state of a changeover switch in a conventional high-frequency switch.
FIG. 8 is a block diagram showing a configuration of a conventional high-frequency amplifier circuit incorporating a gain control function.
FIG. 9 is a circuit diagram showing a configuration of another example of the high-frequency switch according to the first embodiment of the present invention.
10 is a circuit diagram showing an example of a specific configuration of the high-frequency switch / amplifier circuit of FIG. 3. FIG.
11 is a circuit diagram showing another example of a specific configuration of the high-frequency switch / amplifier circuit of FIG. 3;
[Explanation of symbols]
101 Signal input terminal
102 oscillator
103 Upconverter
104 High frequency amplifier circuit
105 high frequency switch
106 Bandpass filter
107 High-power high-frequency amplifier circuit
108 Isolator
109 Band pass filter
110 High power high frequency amplifier circuit
111 Isolator
112 Duplexer
113 Antenna
114 Antenna
115 Signal output terminal
116 Signal output terminal
121 Power supply terminal
122 Ground terminal
123 Reference voltage terminal
124 Control terminal
125 signal input terminal
127 Signal output terminal
128 signal output terminal
131 Field Effect Transistor
132 Field Effect Transistor
181 Signal input terminal
182 Impedance matching circuit
183 Gain control circuit
184 amplifier
185 impedance matching circuit
186 amplifier
187 Impedance matching circuit
188 signal output terminal
189 Control terminal
200 Transmitter of mobile phone terminal
201 Upconverter
202 High-frequency amplifier circuit with variable gain
203 High frequency switch
204 Bandpass filter
205 High power high frequency amplifier
206 Isolator
207 Band pass filter
208 High power high frequency amplifier circuit
209 Isolator
211 Power supply terminal
212 Ground terminal
213 Reference voltage terminal
214 Reference voltage terminal
215 Signal input terminal
216 Signal output terminal
217 Signal output terminal
218 Control terminal
219 Field Effect Transistor
220 Field Effect Transistor
221 resistance
222 resistance
223 resistance
224 resistance
225 resistance
226 resistance
227 resistance
228 resistance
229 resistance
230 Capacitor
231 Capacitor
232 capacitors
233 capacitor
240 Signal input terminal
241 Impedance matching circuit
242 Gain control circuit
243 Control circuit
244 amplifier
245 high frequency switch
246 Impedance matching circuit
247 amplifier
248 Impedance matching circuit
249 Signal output terminal
250 impedance matching circuit
251 amplifier
252 Impedance matching circuit
253 signal output terminal
254 Power supply terminal
255 Power supply terminal
256 Power supply terminal
300 Receiver of mobile phone terminal
301 Front-end IC
302 Bandpass filter
400 Synthesizer part of mobile phone terminal
401 Temperature controlled crystal oscillator (TCXO)
402 Phase Locked Loop (PLL)
403 Voltage controlled oscillator (VCO)
500 Duplexer part of mobile phone terminal
501 antenna
502 Antenna
503 Duplexer

Claims (17)

A signal input terminal;
First and second signal output terminals;
A control terminal to which a control voltage is applied;
One and other signal electrodes and a control electrode, one signal electrode is connected to the signal input terminal, the other signal electrode is connected to the first signal output terminal, and the one and other signal electrodes are connected to the control terminal Each of which is connected to one of the signal input terminals and the other signal signal to the second signal output terminal. A changeover switch having an electrode connected and a second switch element having a control electrode connected to the control terminal;
First and second reference voltages having different values are generated, the first reference voltage is applied to a control electrode of the first switch element, and the second reference voltage is applied to one of the second switch elements and A reference voltage generation circuit for applying to one of the other signal electrodes, and the control based on the relationship between the control voltage and the first reference voltage and the relationship between the control voltage and the second reference voltage. A high frequency switch in which the first and second switch elements are selectively turned on in accordance with a voltage value. The first switch element comprises a first field effect transistor, one of a source electrode and a drain electrode serves as the one signal electrode, the other of the source electrode and the drain electrode serves as the other signal electrode, and a gate electrode serves as the above-mentioned signal electrode. The control electrode,
The second switch element comprises a second field effect transistor, wherein one of a source electrode and a drain electrode serves as the one signal electrode, the other of the source electrode and the drain electrode serves as the other signal electrode, and a gate electrode serves as the above-mentioned signal electrode. The high-frequency switch according to claim 1, which serves as a control electrode. The high frequency switch according to claim 2, wherein the second reference voltage is higher than the first reference voltage. 3. The high frequency switch according to claim 2, wherein a difference between the first reference voltage and the second reference voltage is substantially the same as a threshold value of the first and second field effect transistors. 3. The high frequency switch according to claim 2, wherein the reference voltage generation circuit is constituted by a series circuit of three or more resistors. The field effect transistor includes a source electrode, a drain electrode, and at least one gate electrode, wherein the gate electrode is disposed between the source electrode and the drain electrode, and the gate electrode and the control terminal or the 3. The high frequency switch according to claim 2, wherein an output terminal of the reference voltage generation circuit is connected via a resistor. A signal input terminal;
First and second signal output terminals;
A control terminal to which a control voltage is applied;
A first switch element having one and other signal electrodes and a control electrode, one signal electrode connected to the signal input terminal, and one of the one and other signal electrodes connected to the control terminal; And a second switch element having the other signal electrode and the control electrode, one signal electrode connected to the signal input terminal, and a control electrode connected to the control terminal,
A first amplifier having an input terminal connected to the other signal electrode of the first switch element and an output terminal connected to the first signal output terminal;
A second amplifier having an input terminal connected to the other signal electrode of the second switch element and an output terminal connected to the second signal output terminal;
First and second reference voltages are generated, the first reference voltage is applied to the control electrode of the first switch element, and the second reference voltage is applied to one and the other signals of the second switch element. A reference voltage generation circuit to be applied to any of the electrodes,
Based on the relationship between the control voltage and the first reference voltage, and the relationship between the control voltage and the second reference voltage, the first and second switch elements are changed according to the value of the control voltage. Selectively conducting,
When the first switch element is conductive, the first amplifier is in an operating state, the second amplifier is inactive, and when the second switch element is conductive, the first amplifier is inactive. And a high-frequency switch / amplifier circuit in which the second amplifier is in an operating state. The first switch element comprises a first field effect transistor, one of a source electrode and a drain electrode serves as the one signal electrode, the other of the source electrode and the drain electrode serves as the other signal electrode, and a gate electrode serves as the above-mentioned signal electrode. The control electrode,
The second switch element comprises a second field effect transistor, wherein one of a source electrode and a drain electrode serves as the one signal electrode, the other of the source electrode and the drain electrode serves as the other signal electrode, and a gate electrode serves as the above-mentioned signal electrode. A control electrode,
The first amplifier includes a third field effect transistor or a first bipolar transistor, and a gate electrode or a base electrode serves as an input terminal, a drain electrode or a collector electrode serves as an output terminal, and a source electrode or an emitter electrode serves as a high frequency. Grounded to
The second amplifier includes a fourth field effect transistor or a second bipolar transistor, the gate electrode or the base electrode serves as an input terminal, the drain electrode or the collector electrode serves as an output terminal, and the source electrode or the emitter electrode has a high frequency. The high frequency switch / amplifier circuit according to claim 7, which is grounded. 9. The high frequency switch / amplifier circuit according to claim 8, wherein the second reference voltage is higher than the first reference voltage. 9. The high-frequency switch / amplifier circuit according to claim 8, wherein a difference between the first reference voltage and the second reference voltage is substantially the same as a threshold value of the first and second field effect transistors. 9. The high frequency switch / amplifier circuit according to claim 8, wherein the reference voltage generating circuit is constituted by a series circuit of three or more resistors. 8. The high frequency switch / amplifier circuit according to claim 7, wherein the control terminal and one of the power terminals of the first and second amplifiers are connected in common. A third amplifier having an output terminal connected to the signal input terminal, amplifying a signal input to the input terminal of the third amplifier and inputting the amplified signal to the signal input terminal; 8. The high frequency switch / amplifier circuit according to claim 7, wherein a power supply terminal of the amplifier is connected in common with a power supply terminal of the reference voltage generation circuit. A signal input terminal;
First and second signal output terminals;
A control terminal to which a control voltage is applied;
One and other signal electrodes and a control electrode, one signal electrode is connected to the signal input terminal, the other signal electrode is connected to the first signal output terminal, and the one and other signal electrodes are connected to the control terminal Each of which is connected to one of the signal input terminals and the other signal signal to the second signal output terminal. A changeover switch having an electrode connected and a second switch element having a control electrode connected to the control terminal;
First and second reference voltages having different values are generated, the first reference voltage is applied to a control electrode of the first switch element, and the second reference voltage is applied to one of the second switch elements and A reference voltage generation circuit to be applied to either of the other signal electrodes;
An amplifier having an output terminal connected to the signal input terminal;
Based on the relationship between the control voltage and the first reference voltage, and the relationship between the control voltage and the second reference voltage, the first and second switch elements are changed according to the value of the control voltage. To selectively conduct,
A high frequency switch / amplifier circuit in which a signal input to the input terminal of the amplifier is amplified and input to the signal input terminal, and the power supply terminal of the amplifier is shared with the power supply voltage of the reference voltage generation circuit. A mobile communication terminal having a high-frequency switch having a high-frequency signal path selection function,
The high-frequency switch is a signal input terminal;
First and second signal output terminals;
A control terminal to which a control voltage is applied;
One and other signal electrodes and a control electrode, one signal electrode is connected to the signal input terminal, the other signal electrode is connected to the first signal output terminal, and the one and other signal electrodes are connected to the control terminal Each of which is connected to one of the signal input terminals and the other signal signal to the second signal output terminal. A changeover switch having an electrode connected and a second switch element having a control electrode connected to the control terminal;
First and second reference voltages having different values are generated, the first reference voltage is applied to a control electrode of the first switch element, and the second reference voltage is applied to one of the second switch elements and A reference voltage generation circuit for applying to one of the other signal electrodes, and the control based on the relationship between the control voltage and the first reference voltage and the relationship between the control voltage and the second reference voltage. A mobile communication terminal, wherein the first and second switch elements are selectively turned on according to a voltage value. A mobile communication terminal having a high-frequency switch / amplifier circuit having a high-frequency signal path selection function,
The high frequency switch / amplifier circuit is a signal input terminal,
First and second signal output terminals;
A control terminal to which a control voltage is applied;
A first switch element having one and other signal electrodes and a control electrode, one signal electrode connected to the signal input terminal, and one of the one and other signal electrodes connected to the control terminal; And a second switch element having the other signal electrode and the control electrode, one signal electrode connected to the signal input terminal, and a control electrode connected to the control terminal,
A first amplifier having an input terminal connected to the other signal electrode of the first switch element and an output terminal connected to the first signal output terminal;
A second amplifier having an input terminal connected to the other signal electrode of the second switch element and an output terminal connected to the second signal output terminal;
First and second reference voltages are generated, the first reference voltage is applied to the control electrode of the first switch element, and the second reference voltage is applied to one and the other signals of the second switch element. A reference voltage generation circuit to be applied to any of the electrodes,
Based on the relationship between the control voltage and the first reference voltage, and the relationship between the control voltage and the second reference voltage, the first and second switch elements are changed according to the value of the control voltage. Selectively conducting,
When the first switch element is conductive, the first amplifier is in an operating state, the second amplifier is inactive, and when the second switch element is conductive, the first amplifier is inactive. And a mobile communication terminal in which the second amplifier is in an operating state. A mobile communication terminal having a high-frequency switch / amplifier circuit having a high-frequency signal path selection function,
The high-frequency switch / amplifier circuit is
A signal input terminal;
First and second signal output terminals;
A control terminal to which a control voltage is applied;
One and other signal electrodes and a control electrode, one signal electrode is connected to the signal input terminal, the other signal electrode is connected to the first signal output terminal, and the one and other signal electrodes are connected to the control terminal Each of which is connected to one of the signal input terminals and the other signal signal to the second signal output terminal. A changeover switch having an electrode connected and a second switch element having a control electrode connected to the control terminal;
First and second reference voltages having different values are generated, the first reference voltage is applied to a control electrode of the first switch element, and the second reference voltage is applied to one of the second switch elements and A reference voltage generation circuit to be applied to either of the other signal electrodes;
An amplifier having an output terminal connected to the signal input terminal;
Based on the relationship between the control voltage and the first reference voltage, and the relationship between the control voltage and the second reference voltage, the first and second switch elements are changed according to the value of the control voltage. To selectively conduct,
A mobile communication terminal that amplifies a signal input to an input terminal of the amplifier and inputs the signal to the signal input terminal, and uses a power supply terminal of the amplifier in common with a power supply voltage of the reference voltage generation circuit.

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