JP2003188754A - Local oscillation frequency signal output circuit and portable terminal using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a local oscillation frequency signal output circuit for supplying a local oscillation frequency signal in order to maintain a constant or higher receiving quality all the time and for reducing power consumption. <P>SOLUTION: The local oscillation frequency signal is generated by processing an oscillation signal outputted from a local oscillator 1 with a balun 2, a frequency divider 3 and phase equipment 4, amplified with an amplifier 5 and supplied to a mixer 8 so that differentially converted received signals SR and SR can be converted to a baseband signal BR. The baseband signal BR is detected by a detector 10 and a control part 11 detects the level of the interference signal of the baseband signal BR, that is, a receiving state, from the detection output and generates a control signal SC corresponding to the detected result and reference information in a storage part 12. The gain of the amplifier 5 is controlled by the control signal SC and when the receiving state is pool, the amplitude of the local oscillation frequency signal is made greater. When the receiving state is satisfactory, the amplitude of the local oscillation frequency signal is suppressed so that the receiving quality can be kept constant. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct conversion receiver for directly converting a received signal into a baseband signal, and more particularly to a local oscillation frequency signal output circuit for such direct conversion and a portable terminal using the same. .

[0002]

2. Description of the Related Art In a conventional direct conversion system for directly converting a received signal from a radio frequency signal to a baseband signal by a mixer, a circuit for outputting a local oscillation frequency signal for such frequency conversion (local oscillation frequency signal output circuit ), In order to make the frequency in the IF stage zero, the received signal input to the mixer and the local oscillation frequency signal must have the same frequency, but the oscillation signal output from the local oscillator that becomes the local oscillation frequency signal When the frequency of the received signal is equal, the oscillated signal leaks into the received signal path and DC offset occurs in the received signal, narrowing the dynamic range in the received signal processing circuit and lowering the receiving sensitivity.

In order to avoid this, in the direct conversion system, the frequency of the local oscillation frequency signal is multiplied by an integral multiple of the frequency of the received signal, and the frequency is divided by a frequency dividing circuit to convert it to the same frequency as the received signal (special feature. Kaihei 2001-211
No. 098), or conversely, a format using a local oscillator capable of multiplying a received signal by an integer by a multiplier and outputting an oscillation signal of the same frequency as the multiplied received signal (Japanese Patent Laid-Open No. 11-461).
No. 53).

On the other hand, circuit driving of high-frequency signals requires circuit elements to operate at high speed, and high current consumption is required for the operation. Therefore, in a mobile terminal such as a mobile phone that uses such a circuit element and uses a battery as a power source, power consumption is rapidly performed, which causes a problem that the standby time is reduced.

Further, with an emphasis on reducing current consumption rather than reception deterioration due to DC offset, an oscillator having the same output frequency as the received signal and an element capable of 90 ° phase shift with only a passive element are used to generate an oscillation signal. The format for outputting is also known (ISSCC2001 / SESSION18 / 3G WIRELESS / PAPER 18.
1).

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the case of the prior art described in Japanese Patent No. 211098, in order to reduce the influence of DC offset, the frequency of the local oscillation frequency signal is an integral multiple of the frequency of the received signal, and the local oscillation frequency signal is divided into an integral multiple. A circuit for driving a signal having a higher frequency than the received signal is required, including the circuit. Therefore, a high current consumption is required to drive the circuit, which leads to an increase in power consumption of the entire receiving device.

In addition, the above-mentioned ISSCC2001 / SESSION 18 / 3G WI
In the system described in RELESS / PAPER 18.1, the output frequency of the local oscillator is equal to the received signal.
Since half of the frequency in the conventional technique described in 001-211098 is sufficient, the circuit configuration can be downsized by the amount that the frequency divider is unnecessary, and the frequency is an integral multiple of the received signal. Since it is possible to reduce the current consumption required to obtain the gain of the oscillation signal and the current consumption by reducing the frequency divider, it is possible to expect a large reduction in the current consumption. However, when the desired reception wave level is a weak electric field, there is a problem that DC offset occurs in the mixer output due to leakage of the local oscillation frequency signal, and the reception quality is seriously deteriorated due to the DC offset.

Further, as another problem, in the above-mentioned three conventional methods, the output level of the local oscillation frequency signal is prevented so that distortion due to the interfering wave does not occur even when the expected interfering wave level is input. Is constant. For this reason,
Even if the interference level is low and the reception is good,
The control level remains constant, and the current consumption of the circuit cannot be reduced to lower the level of the oscillation signal.

The present invention has been made in view of the above points, and an object of the present invention is to provide an appropriate level for the receiving state at that time regardless of whether the desired reception wave level is a weak electric field or a strong electric field. An object of the present invention is to provide a local oscillation frequency signal output circuit capable of outputting an oscillation signal, ensuring reception quality and realizing reduction of power consumption, and a mobile terminal using the same.

[0010]

In order to achieve the above object, the present invention is a local oscillation frequency signal output circuit for directly converting a received signal into a baseband signal, the local oscillation frequency signal generating circuit generating an oscillation signal. An oscillator, a processing unit that processes this oscillation signal to generate a local oscillation frequency signal having a frequency equal to the received signal, an amplification unit that amplifies this local oscillation frequency signal, and this local oscillation frequency signal that is output from this amplifier. In order to determine the gain adjustment of this amplifier, the direct conversion section that converts this received signal into a baseband signal, the determination section that determines the level of the interfering wave in this baseband signal obtained by this direct conversion section, The reference level information is compared with the storage unit that stores the reference information of, and the level of the interference signal determined by the determination unit. According to the comparison result and a control unit for generating a control signal for adjusting the gain of the amplifier,
The level of the local oscillation frequency signal output from the amplifier is adjusted according to the level of the interfering signal mixed in the baseband signal.

Further, the present invention is a local oscillation frequency signal output circuit for directly converting a received signal into a baseband signal, which is a local oscillator for generating an oscillation signal and a local oscillation for shifting the phase of the oscillation signal. A phase conversion unit that generates a frequency signal, an amplification unit that amplifies this local oscillation frequency signal, a direct conversion unit that converts this received signal into a baseband signal by this local oscillation frequency signal output from this amplifier, A detection unit that detects the level of this baseband signal obtained by the direct conversion unit, a storage unit that stores reference information for determining the gain adjustment of this amplifier, the detection output of this detection unit, and this reference And a control unit for generating a control signal for adjusting the gain of the amplifier according to the comparison result. Depending on the detection output is used for adjusting the level of the local oscillation frequency signal output from the amplifier section.

The detection unit removes an interfering signal from a first detection circuit for detecting the level of the baseband signal obtained by the direct conversion unit and a detection output of the first detection circuit to obtain a desired signal. And a second detection circuit for detecting the level of this desired signal output from this filter.

The control section obtains the ratio of the detection output levels of the first and second detection circuits and compares it with the reference information stored in the storage section, and according to the comparison result, the amplifier The configuration is such that a control signal for gain adjustment is generated.

Further, the present invention is a local oscillation frequency signal output circuit for directly converting a received signal into a baseband signal, which is a local oscillator for generating an oscillation signal and a local oscillation for shifting the phase of the oscillation signal. A phase conversion unit that generates a frequency signal, an amplification unit that amplifies this local oscillation frequency signal, a direct conversion unit that converts this received signal into a baseband signal by this local oscillation frequency signal output from this amplifier, An A / D converter that converts the baseband signal obtained by the direct conversion unit into a digital signal, a demodulator that demodulates the digital signal, and an error controller that determines the error rate of the demodulated signal from the demodulator. And a control unit that generates a control signal for adjusting the gain of the amplifier according to the determination result of the error rate and the control signal for the control unit. And a D / A converter for converting the log signal and supplying it to the amplifier, and adjusting the level of the local oscillation frequency signal output from the amplifier according to the error rate of the demodulated signal. .

Further, the present invention is a local oscillation frequency signal output circuit for directly converting a received signal into a baseband signal, which is a local oscillator for generating an oscillation signal and a local oscillation for shifting the phase of the oscillation signal. A phase conversion unit that generates a frequency signal, an amplification unit that amplifies this local oscillation frequency signal, a direct conversion unit that converts this received signal into a baseband signal by this local oscillation frequency signal output from this amplifier, An A / D conversion unit that converts the baseband signal obtained by the direct conversion unit into a digital signal, a demodulation unit that demodulates the digital signal, performs processing of the transmission / reception signal, and controls according to the level of the transmission signal. A system control unit that outputs a signal and a D / A that converts the control signal into an analog signal and supplies the analog signal to the amplifier And a section, according to the level of the transmission signal and adjusts the level of the local oscillation frequency signal output from the amplifier section.

Further, the present invention is a local oscillation frequency signal output circuit for directly converting a received signal into a baseband signal, wherein first and second local oscillators for generating the oscillation signal and the oscillation signal thereof are provided. A first circuit block including an amplifying section for amplifying, at least an amplifier, processing the oscillation signal from the first local oscillator to generate a first local oscillation frequency signal, and including at least an amplifier; A second circuit block that processes the oscillation signal from the second local oscillator to generate a second local oscillation frequency signal, and a changeover switch that selects one of the first and second local oscillation frequency signals. And a direct conversion unit that converts this received signal into a baseband signal with the local oscillation frequency signal selected by this changeover switch, and this direct conversion unit A detection unit that detects the level of the obtained baseband signal, a storage unit that stores a determination reference for switching control of the first and second circuit blocks, a detection output of the detection unit, and this determination. Compare with the information,
And a control unit for generating a first control signal for switching between the first and second circuit blocks in accordance with the comparison result, and the first and second control blocks are generated in accordance with the detection output level of the detection unit. The second circuit block is switched.

Each of the first and second circuit blocks has an amplifier, and the control unit is selected by the first control signal of the first and second circuit blocks according to the level of the baseband signal. A second control signal for adjusting the gain of one of the amplifiers is generated.

The amplification section is a variable gain amplification circuit, and the gain is adjusted by a control signal from the control section.

The amplifier section selects one or more fixed gain amplifier circuits for amplifying the local oscillation frequency signal, a line that allows the local oscillation frequency signal to pass through as it is, and one of these fixed gain amplifier and line. It consists of a changeover switch,
The fixed gain amplifier circuit is in an off state when it is not selected by the changeover switch.

The detection unit is a first unit for detecting the level of the baseband signal obtained by the direct conversion unit.
And a filter that removes an interfering signal from the detection output of the first detection circuit to extract a desired signal, and a second detection circuit that detects the level of the desired signal output from the filter. To do.

The control unit is configured to generate the first control signal in accordance with the result of comparison between the level of the detection output of the second detection circuit and the determination standard.

The control unit obtains the ratio of the detection output levels of the first and second detection circuits and compares it with the reference information stored in the storage unit, and adjusts the gain of the amplifier according to the comparison result. The control signal for performing the operation is generated.

In order to achieve the above-mentioned object, the present invention is a portable terminal having a transmission system and a reception system and performing transmission and reception by a common antenna, wherein the reception system directly bases received signals. A direct conversion method for converting to a band signal is used, and any one of the above local oscillation frequency signal output circuits is used as a means for direct conversion of a received signal.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of a local oscillation frequency signal output circuit according to the present invention,
1 is a local oscillator, 2 is a balun, 5 is an amplifier, 3 is a frequency divider, 4 is a phase shifter, and 6 and 7 are LNA (Low Noise Amplifie).
r: low noise amplifier), 8 and 9 are mixers, 10 and 10a-
Reference numeral 10d is a detector, 11 is a control unit, and 12 is a storage unit.

In the figure, radio frequency received signals received by means not shown are supplied to a balun (not shown) and differentially converted to generate received signals SL, SL having mutually opposite phases. It These reception signals SL and SL of radio frequency are amplified by LNAs 6 and 7, respectively, and then supplied to mixers 8 and 9 as direct conversion units.

On the other hand, the local oscillator 1 outputs an oscillation signal having a frequency that is an integral multiple of these received signals SL, SL, for example, twice, and a processing unit including a balun 2, a frequency divider 3 and a phase shifter 4. Is supplied to. In this processing unit, the supplied oscillating signal is differentially converted by the balun 2, and the oscillating signals SL and S having a frequency equal to the oscillating signal and having a phase opposite to each other.
L is generated. These oscillation signals SL and SL are divided by the frequency divider 3
Is supplied to the phase shifter 4 serving as a phase converter. In the phase shifter 4, from the oscillation signals SL and SL, an I signal having the same phase as the oscillation signal SL, an I signal having a phase opposite to the oscillation signal SL, and a Q having a 90 ° phase difference from the oscillation signal SL.
A signal and a Q signal having a 90 ° phase difference with the oscillation signal SL are generated. The I, I, Q, and Q signals output from the phase shifter 4 are amplified by the variable gain amplifier 5, and then supplied to the mixers 8 and 9 as local oscillation frequency signals.

That is, in the mixer 8, the reception signals SR, SR of the radio frequency from the LNAs 6, 7 are the local oscillation frequency signals I, I (hereinafter referred to as I, I signals) having the same frequency.
The baseband signal BR is mixed by
1, the frequency is converted to BR2. Similarly, mixer 9
Then, the received signals SR and S of the radio frequency from the LNAs 6 and 7
R is a local oscillation frequency signal Q, Q having a frequency equal to this
By being mixed with (hereinafter, referred to as Q and Q signals), the frequency is converted into baseband signals BR3 and BR4. These baseband signals BR1 to BR4 are supplied to the detector 10, and the detectors 10c, 10d and 10 are supplied to the respective detectors.
It is detected at a and 10b. These detectors 10a to 10d
The detection output of is supplied to a processing unit (not shown) such as a demodulator.

Further, the detection output Dt of each of the detectors 10a to 10d is supplied to the control unit 11. The control unit 11 processes the detected outputs based on the reference information stored in the storage unit 12 to generate the control signal SC, and the gain of the amplifier 5 is adjusted by the control signal SC.

2A and 2B show I,
It is a block diagram which shows the specific example of the amplifier 5 for every Q, I, and Q signal, 13 is a variable gain circuit, 14 is a fixed gain circuit, 1
Reference numerals 5 and 16 are changeover switches.

The concrete example shown in FIG. 2A is a variable gain circuit 1.
3 is used, and the gain is changed in multiple stages (or continuously) by adjusting the current consumption of the variable gain circuit 13 by the control signal SC from the control unit 11 (FIG. 1). You can

The concrete example shown in FIG. 2B is a fixed gain circuit 1.
4 and changeover switches 15 and 16, and these changeover switches 15 and 16 are provided in the control unit 11
A control signal SC from (FIG. 1) switches and operates in synchronization with each other. A fixed gain is connected between the A contacts between the change-over switches 15 and 16, and these B contacts are connected to each other. A switch switching type amplifier circuit using the
The gain can be switched by controlling the ON / OFF control of 4 and the switches 15 and 16 at both ends. When the changeover switches 15 and 16 are switched to the A contact side, the fixed gain circuit 14 is operated (ON) by the control signal SC, and a signal passing from the changeover switch 15 side to the changeover switch 16 side is changed by the fixed gain circuit 14. The fixed gain circuit 14 is amplified by the gain set in the fixed gain circuit 14. When the changeover switches 15 and 16 are switched to the A contact side, a signal passes from the changeover switch 15 to the changeover switch 16 with a gain of 1. At this time, the fixed gain circuit 14 is set to the OFF state by the control signal SC to prevent wasteful current consumption in the fixed gain circuit 14.

In the specific example shown in FIG. 2B, one fixed gain circuit 14 is used. However, a plurality of fixed gain circuits having different set gains are provided in parallel, and any one of these fixed gain circuits is provided. One of them may be selected by the changeover switches 15 and 16 under the control of the control signal SC. As a result, multi-step gain adjustment can be performed.

FIG. 3 shows the detectors 10a to 10d in FIG.
It is a block diagram which shows one specific example (Hereinafter, these are called the detector 10), 17 is a detection circuit, 18 is a filter, 19 is a detection circuit.

In the figure, the baseband signal BR (any one of the baseband signals BR1 to BR4) output from either the mixer 8 or 9
First, it is supplied to the detection circuit 17 and detected, and the detection output (detection signal) is supplied to the filter 18 to remove interference signals such as noise. The desired signal obtained by removing the interfering signal by the filter 18 is supplied to a demodulator in the subsequent stage (not shown) via the detection circuit 19.

In such a configuration, the detection circuit 17
The level of the obtained detection signal is detected, and the signal representing the level, that is, the detection output Dt1, is used as the control unit 11
(FIG. 11), and the detection circuit 19 detects the level of the desired signal supplied from the filter 18,
This is supplied to the control unit 11 as the detection output Dt2.

Therefore, in FIG.
First, the detection output D supplied from the detector 10 shown in FIG.
The level ratio Dt2 / Dt1 (≦ 1) between t1 and Dt2 is obtained. The level ratio Dt2 / Dt1 corresponds to the level of the interfering signal mixed with the baseband signal or the level of the desired signal, and the less the interfering signal is, that is, the better the baseband signal is, the larger the value is close to 1. Become.

Then, the control section 11 fetches the reference information from the storage section 12, the baseband signal contains a lot of interfering signals and the level of the desired signal is small, and the level ratio Dt2 / Dt1 at that time is shown in FIG. When the value is smaller than the specified range determined by the reference information as shown, the current consumption of the amplifier 5 is increased to increase its gain,
Increase the amplitude of the I, Q, I, Q signals to increase the level ratio Dt2 / D
The baseband signal B is set so that t1 falls within this specified range.
Increase the level of R1 to BR4. In this case, the mixer 8,
It goes without saying that the gain of the amplifier 5 is increased to such an extent that distortion does not occur at 9. As a result, the detector 1
From 0, it is possible to obtain a desired signal of a good level in which the interfering signal is suppressed.

Further, the control unit 11 determines that the level of the desired signal is large and the level ratio Dt2 / Dt1 is larger than the specified range determined by the reference information as shown in FIG. , By reducing the current consumption of the amplifier 5 and lowering its gain,
Decrease the amplitude of the Q, I, Q signals and set the level ratio Dt2 / Dt1.
So as to be within the specified range, the baseband signal BR1
~ Try to lower the level of BR4. In this case, to the extent that distortion does not occur in the baseband signals in the mixers 8 and 9,
It goes without saying that the gain of the amplifier 5 is lowered. As a result, the desired signal of an appropriate level in which the interfering signal is suppressed is obtained from the detector 10, but the current consumption of the amplifier 5 is reduced to prevent an excessive current consumption. Therefore, the power consumption of the amplifier can be reduced.

By the way, the detector 10 in FIG. 1 has the detectors 10c, 10d, 1 for each of the baseband signals BR1 to BR4.
Since they are 0a and 10b, the detection outputs Dt1 and Dt2 shown in FIG. 3 are obtained respectively. In the control unit 11, the level ratio Dt1 / Dt2 with the detection outputs Dt1 and Dt2 is obtained for each of the detectors 10a to 10d, and the worst state among them is shown, that is, the minimum level ratio Dt1 / Dt2 is selected,
With this, the above-mentioned amplifier 5 is controlled.

Next, according to the flow chart shown in FIG.
The control operation of the controller 11 will be described in more detail.

In FIG. 5, the detection circuit 1 of each detector 10 is shown.
When the detection outputs Dt1 and Dt2 are supplied from 7 and 19 (FIG. 3) (step 100), the amplifier 5 from the storage unit 12 is supplied.
Reference information, which is a reference for determining whether or not the gain adjustment is possible (FIG. 1), is acquired (step 101), and as a result, a specified range is set as shown in FIG. Then, the level ratio Dt2 / Dt1 is obtained for each detector 10 and the level ratio D of the minimum value is obtained.
Select t2 / Dt1 as the target level ratio, compare this target level ratio Dt2 / Dt1 with the range defined by the reference information (step 102), and determine whether or not the gain adjustment of the gain of the amplifier 5 is possible (steps 103 and 106). ).

Here, the target level ratio Dt2 / Dt1
Is smaller than the specified range (step 103),
The amplitude adjustment information of the output level of the amplifier 5 in this case is acquired from the storage unit 12 (step 104), and the control signal SC (FIG. 1) based on this is sent to the amplification unit 5. This allows
In the amplification section 5, gain adjustment is performed to increase the gain by one predetermined step (step 105). When the target level ratio Dt2 / Dt1 is larger than the specified range (step 106), amplitude adjustment information of the output level of the amplifier 5 in this case is acquired from the storage unit 12 (step 1).
07), and the control signal SC (FIG. 1) based on this
Send to. As a result, in the amplification section 5, gain adjustment is performed to reduce the gain by a predetermined one step (step 10).
8). Furthermore, when the target level ratio Dt2 / Dt1 is within the specified range, the control signal SC is not output, and the amplifier 5 maintains the gain at that time as it is.

The above operation is performed in a predetermined cycle,
After the gain adjustment to increase the gain is made (step 10
5) When the target level ratio Dt2 / Dt1 is still smaller than the specified range in the next cycle (step 103), the operations of steps 104 and 105 are performed again to increase the gain of the amplifier 5 and the target level ratio Dt2. It is repeated until / Dt1 is within the specified range. Target level ratio Dt2
The same applies when / Dt1 is larger than the specified range, and the operation of lowering the gain of the amplifier 5 is repeated until the target level ratio Dt2 / Dt1 falls within the specified range. Then, when the target level ratio Dt2 / Dt1 falls within the specified range, the gain of the amplifier 5 is maintained as it is until it goes out of the specified range.

As described above, in the first embodiment,
By controlling the gain of the amplifier according to the reception level and changing the current consumption, it is possible to output a local oscillation frequency signal at a level suitable for the reception state, and if the reception state is good, the local oscillation frequency signal can be output. The power consumption of the amplifier 5 can be reduced and the power consumption can be reduced.

FIG. 6 is a block diagram showing a second embodiment of the local oscillation frequency signal output circuit according to the present invention.
Is GCA (Gain Control Amplifier)
1 / filter section, 21 is an A / D (analog / digital) conversion section, 22 is a demodulation section, 23 is an error control section, 24 is a control section, and 25 is a D / A conversion section (digital / analog). The same reference numerals are given to the portions corresponding to, and redundant description will be omitted.

In the figure, the mixers up to the mixers 8 and 9 have the same structure and operation as those of the first embodiment shown in FIG.

The baseband signals output from the mixers 8 and 9 are supplied to the GCA / filter 20 where they are subjected to interfering wave elimination processing and constant gain control processing in the GCA. The baseband signal output from the GCA / filter 20 is supplied to the A / D converter 21, the baseband signals BR1 and BR2 are added and converted into a digital signal, and the baseband signals BR3 and BR4 are added. Are converted to digital signals. These digital signals are added and demodulated by the demodulation unit 22.

In the second embodiment, the current consumption of the amplifier 5 is adjusted according to the error rate of the demodulated signal from the demodulation section 22 to adjust the gain. Will be described with reference to the flowchart shown in FIG.

As described above, the baseband signal is demodulated by the demodulation unit 22 (step 200), and the error control unit 23.
Then, the error rate of the demodulated signal is measured (step 20).
1). This error rate takes a large value when the demodulated signal has few errors. The control unit 24 fetches the reference information for setting the prescribed range of the error rate as described in FIG. 4 from the storage unit 26, compares this with the error rate (step 202), and determines whether or not the gain adjustment of the amplifier 5 is possible. (Step 20
3,206).

When the result of this determination is that the detected error rate is smaller than the specified range and there are many errors in the demodulated signal (step 203), the control section 24 provides information for increasing the gain of the amplifier 5 from the storage section 26. Capture and generate a digital control signal (step 204). This digital control signal is converted into an analog control signal SC by the D / A conversion section 25, supplied to the amplifier 5 and subjected to gain adjustment in the direction in which its gain increases (step 205). Also,
As a result of the judgment, when the detected error rate is larger than the specified range and the demodulated signal has very few errors (step 20).
6), information for reducing the gain of the amplifier 5 is fetched from the storage unit 26 to generate a digital control signal (step 207). The digital control signal is converted into an analog control signal SC by the D / A converter 25 and supplied to the amplifier 5 for gain adjustment in the direction in which the gain is reduced (step 208). As a result of the judgment, when the detected error rate is within the specified range (steps 203, 20)
6) The control signal SC is not output, and the gain of the amplifier 5 is maintained as it is.

In this way, as in the first embodiment, when the detected error rate is smaller than the specified range and the demodulated signal has many errors (step 203), steps 200 to 200 are repeated until it falls within the specified range. The control operation of 205 is repeated, and if the detected error rate is larger than the specified range and the demodulated signal has very few errors (step 20).
6), Steps 200-2 until this falls within the specified range
The control operations of 03, 206 to 208 are repeated.

As described above, also in the second embodiment, by controlling the gain of the amplifier 5 according to the reception level and adjusting the current consumption, a local oscillation frequency signal of a level suitable for the reception state is obtained. Obtainable. Also,
If the reception state is good, the level of the local oscillation frequency signal is lowered, and accordingly, the current consumption of the amplifier 5 can also be reduced and the power consumption can be reduced.

FIG. 8 is a block diagram showing a third embodiment of the local oscillation frequency signal output circuit according to the present invention.
Is a system control unit, and 28 is a D / A conversion unit. Parts corresponding to those in FIG.

In a mobile terminal such as a mobile phone, the received signal level varies depending on the distance from the base station, but the transmission output level is controlled according to the distance from the base station. In the third embodiment, the gain of the amplifier 5 is controlled according to the transmission output level. Therefore, when the distance to the base station is long, the transmission output level is increased.

By the way, in a mobile terminal such as a mobile phone that performs simultaneous transmission / reception (full-duplex) communication, when the transmission output level increases in this way, the transmission signal leaks into the reception system and enters the reception signal as an interference signal. become. The third embodiment solves such a problem.

In FIG. 8, the system control unit 27 processes the demodulated signal of the demodulation unit 22, and also determines the distance to the base station based on the reception intensity measured by the mobile terminal and the command from the base station. Then, the transmission output level is controlled according to the determination result. Therefore, the system control unit 27
Outputs a digital control signal in response to a change in the transmission output level according to the determined distance. This control signal is converted into an analog control signal SC by the D / A converter 28, and the gain of the amplifier 5 is controlled by this control signal SC. According to this, the received signal level changes according to the distance to the base station, and accordingly the amplifier 5
By adjusting the gain of, good demodulation output can be obtained.

Next, the operation will be described in more detail with reference to the flow chart shown in FIG.

The system control unit 27 performs a receiving process of the baseband signal demodulated by the demodulating unit 22 (step 300) and then performs a control process of a transmission system (not shown).
The transmission output level is compared with a reference value that determines a preset specified range (step 301). When the transmission output level is higher than this specified range (step 302),
Correspondingly, predetermined information is fetched from a storage unit (not shown) (step 303), and a digital control signal corresponding to this information is output. This digital control signal is converted into an analog control signal SC by the D / A conversion unit 28, and then the amplifier 5
Is supplied to. Here, when the transmission output level is higher than the above-mentioned specified range, the distance to the base distance is large and the reception signal level is small, so that the gain of the amplifier 5 is increased by this control signal SC. (Step 304). When the transmission output level is smaller than this specified range (step 305),
Predetermined information corresponding to this is fetched from a storage unit (not shown) (step 306) and a digital control signal corresponding to this information is output. This digital control signal is converted into an analog control signal SC by the D / A conversion unit 28, and then the amplifier 5
Is supplied to. Here, when the transmission output level is smaller than the specified range, the distance to the base distance is small and the reception signal level is large. Therefore, the gain of the amplifier 5 is increased or decreased by the control signal SC. (Step 307).

In this way, also in the third embodiment, the gain control of the amplifier 5 is performed according to the output level of the transmission system and the current consumption is adjusted, so that it is constant regardless of interference from the transmission side. It is possible to output a local oscillation frequency signal capable of maintaining a level reception state. Further, if the reception state is good, the level of the local oscillation frequency signal can be reduced, and accordingly, the current consumption in the amplifier 5 can be reduced and the power consumption can be reduced.

FIG. 10 is a block diagram showing a fourth embodiment of the local oscillation frequency signal output circuit according to the present invention.
a and 1b are local oscillators, 2a and 2b are baluns, 10 'is a detector, 11' is a control unit, 12a and 12b are storage units, 2
Reference numerals 9a and 29b are circuit blocks and reference numerals 30a and 30b are changeover switches. The same reference numerals are given to the portions corresponding to those in FIG.

The fourth embodiment includes a system for generating a local oscillation frequency signal from an oscillation signal having a frequency that is an integral multiple of the reception signal and a system for generating a local oscillation frequency signal from an oscillation signal equal to the reception signal. One of the lines is selected and used.

In FIG. 10, the local oscillator 1a outputs an oscillation signal having a frequency equal to the radio frequency of the received signal (for example, 2 GHz), and the local oscillator 1b outputs an integral multiple of this radio frequency (here, doubled). , Therefore 4 GHz) is output. Oscillation signals output from the local oscillators 1a and 1b are baluns 2 respectively.
The oscillation signals SL, SL and the oscillation signals SL ', S, which are supplied to a and 2b and are differentially converted, and whose phases are mutually inverted.
L'is generated. The oscillation signals SL, SL are supplied to the circuit block 29a to generate I, Q, I, Q signals having a frequency equal to the radio frequency of the received signal, and the oscillation signals SL ', SL', SL 'is supplied to the circuit block 29b, and similarly, I', Q ', I', and Q'signals having frequencies equal to the radio frequency of the received signal are generated. The changeover switches 30a and 29b are the control unit 11 '.
The circuit block 29a side or the circuit block 29b side is selected by the control signal SC from. Therefore, when the changeover switch 30a selects the I signal from the circuit block 29a and supplies it to the mixer 9, the changeover switch 3
0b selects the Q and Q signals from the circuit block 29a and supplies them to the mixer 8, and the changeover switch 30a selects the I ′ and I ′ signals from the circuit block 29b and selects the mixer 9
When the signal is supplied to the mixer 8, the changeover switch 30b selects the Q ′ and Q ′ signals from the circuit block 29b and supplies them to the mixer 8.

In this way, the mixers 9 and 8 receive either the I, Q, I, Q signals from the circuit block 29a or the I ', Q', I ', Q' signals from the circuit block 29b. One of them is supplied and the received signals from the LNAs 6 and 7 are converted into baseband signals.

The baseband signals from the mixers 9 and 8 are supplied to the detector 10 ', and the detection output Dt is supplied from the detector 10' to the controller 11 'as in the first embodiment. The control unit 11 'performs selection of the circuit block 29a side and the circuit block 29b side and the gain adjustment of the amplifier in the selected circuit block 29a or 28b based on the detected output Dt. When receiving a strong electric field,
The circuit block 29a side that handles an oscillation signal having a frequency equal to the radio frequency of the received signal is selected. This can reduce power consumption as compared with the case where the frequency of the oscillation signal is an integral multiple of the radio frequency of the reception signal. However, even if the oscillation signal leaks to the reception signal and a DC offset occurs, a strong electric field is received. Therefore, the influence of the DC offset is small, and therefore the power consumption by the configuration circuit can be suppressed without considering the DC offset. Further, when receiving a weak electric field, the circuit block 29b side that handles an oscillation signal having a frequency equal to an integral multiple of the radio frequency of the received signal is selected. This is because it is necessary to focus on the deterioration of the reception quality due to the DC offset rather than the reduction of the power consumption.

The circuit block 2 is stored in the storage unit 12a.
Reference information necessary to generate a control signal SC for adjusting the gain of an amplifier (not shown) in 9a is stored, and the storage unit 12b stores an amplifier (not shown) in the circuit block 29b. The reference information necessary to generate the control signal SC for the gain adjustment (1) is stored.

FIG. 11 is a circuit block 29 in FIG.
It is a block diagram which shows one specific example of a, 31 is an amplifier, 32 is a polyphase filter (PolyPhase Filter), 33,
34 is an amplifier.

In the figure, the oscillation signal S from the balun 2a (FIG. 10) having a frequency equal to the radio frequency of the received signal.
The L and SL are amplified by a variable gain amplifier 31 and then supplied to a polyphase filter 32 including resistors and capacitors which are passive elements. This polyphase filter 32 has 9
It has a function of 0 ° phase shift and an output branch, and generates I, I, Q and Q signals from the oscillation signals SL and SL, respectively. The generated I and I signals are amplified by the variable gain amplifier 33 and then supplied to the changeover switch 30a (FIG. 10). Further, the generated Q and Q signals are amplified by the variable gain amplifier 34 and then supplied to the changeover switch 30b (FIG. 10).

Here, in the amplifiers 31, 33, and 34, the current consumption is adjusted and the gain is controlled by the control signal SC from the control unit 11 '(FIG. 10) like the amplifier 5 in FIG. However, when the other circuit block 29b is selected, it is set to the non-operational OFF state to suppress the power consumption. Further, since the polyphase filter 32 is composed of passive elements, power consumption there can be suppressed.

FIG. 12 is a circuit block 29 in FIG.
35 is a block diagram showing a specific example of b, 35 is an amplifier,
36 is a flip-flop circuit, and 37 and 38 are amplifiers.

In the figure, the balun 2b (FIG. 1) having a frequency that is an integral multiple (two in this case) of the radio frequency of the received signal is used.
Oscillation signals SL ′ and SL ′ from 0) are amplified by a variable gain amplifier 35 and then supplied to a flip-flop circuit 36. This flip-flop circuit 36 divides the frequency by 2 and
It has a function of 0 ° phase shift and an output branch, and outputs I ′ and I ′ signals from the oscillation signals SL ′ to the oscillation signal S.
Q'and Q'signals are respectively generated from L '. The generated I ′ and I ′ signals are amplified by the variable gain amplifier 37 and then supplied to the changeover switch 30a (FIG. 10). Further, the generated Q ′ and Q ′ signals are used for the gain variable amplifier 3
After being amplified by 8, it is supplied to the changeover switch 30b (FIG. 10).

Here, in the amplifiers 35, 37, 38, the current consumption is adjusted and the gain is controlled by the control signal SC from the control unit 11 '(FIG. 10), like the amplifier 5 in FIG. However, when the other circuit block 29a is selected, it is set to a non-operational OFF state to suppress power consumption.

Here, the oscillation signals SL 'and SL' are used here.
However, in general, when the frequency of the oscillation signals SL ′, SL ′ is an integer n times the radio frequency of the received signal, the flip-flop circuit 3
It goes without saying that the number 6 is configured to be capable of dividing by n.

FIG. 13 is a block diagram showing a specific example of the detector 10 'for each baseband signal in FIG. 10, in which 17' is a detection circuit, 18 'is a filter, and 19' is a detection circuit.

In this figure, this specific example also has the same configuration as the detector 10 in FIG. 1 shown in FIG. That is, the detection circuit 17 'has the same function as the detection circuit 17 in FIG. 3, and the filter 18' and the detection circuit 19 'are also shown in FIG.
It has the same functions as the filter 18 and the detection circuit 19 in FIG. Accordingly, the detection output Dt1 of the baseband signal BR in which the desired signal and the interfering signal are mixed is output from the detection circuit 17 '.
Is output to the control unit 11 ′ (FIG. 10), and the detection circuit 19 ′ outputs the detection output Dt2 of the desired signal obtained by removing the interference signal from the detection output of the detection circuit 17 ′. '(FIG. 10).

In the fourth embodiment, as described above,
One of the circuit blocks 29a and 29b is selected according to the received electric field strength, and the changeover switches 30a and 30b supply the outputs of the selected circuit block to the mixers 8 and 9 as local oscillation frequency signals. The electric field strength is determined by using the detection output Dt2 of the desired signal from the detection circuit 19 'in the detector 10'. The operation of the control unit 11 'for this purpose will be described below with reference to FIG.

The determination of the reception strength for switching the circuit blocks 29a and 29b is made by checking whether the reception electric field strength has changed (that is, the reception electric field strength changes from a strong electric field to a weak electric field or from a weak electric field to a strong electric field). Change or the received electric field strength does not change), and the reference determination information for that is stored in the storage unit 12a. Also,
Similar to the reference information stored in the storage unit 12 of FIG. 1, the reference information for setting the specified range described in FIG. 4 is stored in the storage unit 12b.

In FIG. 14, when the detection output Dt2 is supplied from the detection circuit 19 '(step 400), the control section 11' acquires the reference judgment information from the storage section 12a (step 401) and outputs it as the detection output. By comparing with Dt2 and determining whether the received electric field strength has changed, it is determined whether the circuit blocks 29a and 29b need to be switched (step 402). In this case as well, the reference determination information sets a prescribed range (hereinafter referred to as a switching unnecessary range) as in FIG. 4, and when the detection output Dt2 is within the switching unnecessary range, the circuit blocks 29a and 29b.
The control signal SC for the selective switching is not used, the circuit block currently used is used as it is, and the states of the changeover switches 30a and 30b are maintained as they are.

Further, when the received electric field strength changes from the strong electric field to the weak electric field, the circuit block 29a is selected and used until this time, and the circuit block 29b side is in a state where the power consumption is suppressed. However, the detection output Dt2 becomes smaller than the switching unnecessary range, and it is determined that the circuit block needs to be switched (step 402). As a result, the control unit 11 'generates the control signal SC for this switching (step 403), and the selection is switched from the circuit block 29a to the circuit block 29b by the control signal SC, and the operation of the circuit block 29b is turned on. , Circuit block 2
9a is in a state in which the power consumption of operation OFF is suppressed,
Further, the changeover switches 30a and 30b are the circuit block 29.
The output of b is selected and supplied to the mixers 8 and 9, and the local oscillator 1a is stopped (step 404).

When the received electric field strength changes from a weak electric field to a strong electric field, the circuit block 29b is selected and used until this time, and the circuit block 29a side is in a state where the power consumption is suppressed. However, the detection output Dt2 becomes larger than the switching unnecessary range, and it is determined that the circuit block needs to be switched (step 402). As a result, the control unit 11 'generates the control signal SC for this switching (step 403), and the selection is switched from the circuit block 29b to the circuit block 29a by the control signal SC, and the circuit block 29a is turned on. , Circuit block 2
9b is in a state in which the power consumption of operation OFF is suppressed,
Further, the changeover switches 30a and 30b are the circuit block 29.
The output of a is selected and supplied to the mixers 8 and 9, and the local oscillator 1b is stopped (step 404).

The comparison between the detection output Dt2 and the reference determination information is periodically performed, and when the determination that switching is required is obtained (step 402), the circuit block is switched as described above, but the detection is performed. When the output Dt2 is held within the switching unnecessary range and the received electric field strength does not change,
The circuit blocks used so far are continuously used, and the current state is maintained.

The switching unnecessary range is a range in which the detection output Dt2 exists when the level ratio Dt2 / Dt1 is within the specified range shown in FIG.

In the fourth embodiment, the control unit 11 'for the selected circuit block 29a or 29b is the same as in the first embodiment, in addition to the above-described operation of determining the received electric field strength. The amplifiers 31, 33, 3
4 (FIG. 11) or amplifiers 35, 37, 38 (FIG. 12)
The gain is adjusted. This will be described with reference to FIG.

In the figure, when the detector outputs Dt1 and Dt2 are supplied from the detector 10 '(FIG. 13) (step 5).
00), after the operation described with reference to FIG. 14, the reference information is fetched from the storage unit 12b and the specified range is set as shown in FIG. 4 (step 501). Then, the level ratio Dt2 / Dt1 of the detected outputs Dt1 and Dt2 is obtained and compared with this reference information, and it is determined whether or not the level ratio Dt2 / Dt1 is within the specified range (step 502). In this case, the level ratio Dt2 / Dt applied to each baseband signal from the mixers 8 and 9 is the same as in the first embodiment.
1 is obtained, and one of them is selected as a target as described above.

When the target level ratio Dt2 / Dt1 is within the specified range (step 503), the amplifier of the operating circuit block 29a or 29b (FIGS. 11 and 1).
2) is maintained as it is, but the target level ratio D
When t2 / Dt1 is smaller or larger than the specified range (step 503), the amplitude adjustment information of the output level of the amplifier is acquired from the storage unit 12b (step 504), and the control signal SC based on this is operated. To the circuit block (step 505), and the gain of the amplifier section is adjusted by increasing or decreasing by one step (step 506). Then, such an operation is repeated in a predetermined cycle until the target level ratio Dt2 / Dt1 falls within the specified range.

In this way, the target level ratio Dt2 / D
When t1 is larger than the specified range, the control unit 11 ′ sends the control signal SC to the amplifier of the circuit block 29a or 29b to reduce the current consumption, thereby reducing the amplitude of the received signal to a level at which the distortion of the received signal does not deteriorate. When the target level ratio Dt2 / Dt1 is smaller than the specified range, the current consumption of the amplifier is increased to raise the amplitude value to a level at which the received signal does not deteriorate due to distortion.

As described above, in the fourth embodiment,
By controlling the gain of the amplifier according to the reception level and adjusting the current consumption, it is possible to output a local oscillation frequency signal at a level suitable for the reception state. If the reception condition is good, the level of the local oscillation frequency signal can be lowered,
As a result, the current consumption of the amplifier can be reduced and the power consumption can be suppressed.

Similarly, by switching the circuit blocks according to the reception level, the frequency of the local oscillation frequency signal to be output is reduced from an integral multiple of the received signal to the equal multiple of the received signal. It is possible to reduce the current consumption required for the power consumption.

Therefore, since the gain control of these amplifiers and the selection of the circuit block are performed in parallel, the current consumption can be greatly reduced and the power consumption can be greatly reduced.

FIG. 16 is a block diagram showing an embodiment of a mobile terminal such as a mobile phone using the local oscillation frequency signal output circuit according to the present invention, and 39 is the local oscillation frequency signal output circuit shown in FIG. Local buffer unit of the third embodiment, 40 is a baseband unit, 41 is a microphone or speaker, 42 is an A / D converter or D / A converter, 43 is a control system, 44 is an audio channel codec, and 45 is a baseband. (BB) Modem, 46 is D / A
Converter or A / D converter, 47a and 47b are mixers, 48 is an adder, 49 is an amplifier, 50 is a BPF
(Band pass filter), 51 is a mixer, 52 is an amplifier, 53 is a BPF, 54 is a power amplifier, 55 is a transmission / reception duplexer (DPX), 56 is a transmission / reception antenna, 57 is a differential converter, and 58 is an LPF ( Low-pass filter), 59 is an amplifier, 60 is an LPF, and 61 is an amplifier.

In the portable terminal of this embodiment, the third embodiment shown in FIG. 18 is used as the local oscillation frequency signal output circuit, but the local oscillation frequency signal output circuit of another embodiment is used. You may use.

In FIG. 16, the configuration of this embodiment is as follows.
In general, the base band unit 40, a transmission system, a reception system, a transmission / reception antenna 56 for transmission / reception, and a transmission / reception demultiplexer 55 are included. Here, a direct conversion method is used in which a received signal of a radio frequency is directly converted into a baseband signal, and for this purpose, a local oscillation frequency signal output circuit according to the present invention is used.

The baseband unit 40 processes the audio signal from the microphone 41 to create a baseband signal, sends it to the transmission system, and processes the baseband signal of the audio signal from the reception system to produce a speaker. It is output to 41. The audio signal input from the microphone 41 is converted into a digital audio signal by the A / D converter 42 and supplied to the system control unit 43. The digital audio signal processed by the system control unit 43 is the audio channel codec 44.
After being encoded by, and modulated by the baseband modem 45, it is sent to the transmission system.

In the transmission system, the modulated voice signal is transmitted to the mixer 47.
a, 47b. In the mixer 47a, the modulated audio signal is separately mixed with the oscillation signals whose phases are different from each other by 90 ° to form two intermediate frequency signals whose phases are different from each other by 90 °, and in the mixer 47b, each of them is supplied to the mixer 47a. Two oscillating signals different in phase from the oscillating signal are mixed separately to form two intermediate frequency signals 90 ° out of phase. In this way, the mixers 47a, 47b
From, four intermediate frequency signals whose phases differ by 90 ° are obtained. In the adder 48, these intermediate frequency signals are added with two intermediate frequency signals from the mixer 47a, which are out of phase with each other by 90 °, and are added with two intermediate frequency signals from the mixer 47b, which are out of phase with each other by 90 °. It These two added signals are fed to the amplifier 49 and BPF5.
0 to the mixer 51 and mixed with the signals of the corresponding phases of the I and I signals from the local buffer section 39 of the local oscillation frequency signal output circuit according to the present invention to obtain two addition signals of radio frequency. To be These addition signals are
It is supplied to the power amplifier 54 via the amplifier 52 and the BPF 53, and these are combined and amplified together. As a result, a transmission signal is obtained from the power amplifier 54, and this transmission signal is transmitted from the transmission / reception antenna 56 via the transmission / reception duplexer 55.

Next, in the reception system, the reception signal from the transmitting / receiving antenna 56 is supplied to the differential converter 57 via the transmission / reception duplexer 55, and is converted into two reception signals whose phases are different by 180 °. It These are the received signals SR, SR in FIG. 8, and as described in FIG. 8, I, Q, I, from the local buffer unit 39 are mixed in the mixers 6, 7.
Mixed with the Q signal, four baseband signals are obtained. Each of these four baseband signals is represented by G in FIG.
After being processed by the LPFs 58 and 60 and the amplifiers 59 and 61 that form the CA / filter unit 20, they are supplied to the baseband unit 40.

In the baseband section 40, these four baseband signals are converted into digital signals by the A / D converter 46 corresponding to the A / D conversion section 22 in FIG. 8, and then the demodulation section in FIG. 22 is demodulated by the baseband modem 45 and is decoded by the audio channel codec 44 to be a digital audio signal. This digital audio signal is processed by the system control unit 43 corresponding to the system control unit 27 in FIG. 8, restored to an analog audio signal by the D / A converter 42, and supplied to the speaker 41.

Further, as described with reference to FIG. 8, the system control section 43 outputs a digital control signal according to the transmission output level, and this digital control signal corresponds to the D / A conversion section 28 in FIG. The D / A converter 46 converts the analog control signal SC. The control signal SC is supplied to the local buffer unit 39, and as a result, the gain of the amplifier 5 is adjusted as described with reference to FIG.

As described above, also in this embodiment, even if the received signal level changes, the amplitude of the local oscillation frequency signal from the local oscillation frequency signal output circuit according to the present invention is adjusted accordingly. , The optimum level of the baseband signal can be obtained, and when the reception level is good, the amplitude of the local oscillation frequency signal is suppressed to the extent that distortion does not occur, and as described above, the power consumption is reduced. Reduction can be realized.

[0098]

As described above, according to the present invention,
The level of the local oscillation frequency signal for direct conversion of the received signal is adjusted according to the receiving condition, and the condition is equivalent to that in which the signal was received in good condition.Therefore, keep the receiving quality above a certain level. While enabling
A reduction in power consumption can be realized.

Further, since the circuit block for generating the local oscillation frequency signal is switched according to the reception state and the circuit block adapted to the reception state is used, it is necessary to maintain the reception quality above a certain level. In addition to being possible, reduction of power consumption can be realized.

[Brief description of drawings]

FIG. 1 shows a first local oscillator frequency signal output circuit according to the present invention.
It is a block diagram showing an embodiment of.

FIG. 2 is a configuration diagram showing a specific example of the amplifier in FIG.

FIG. 3 is a block diagram showing a specific example of the detector shown in FIG.

FIG. 4 is a diagram for explaining reference information in a control unit in FIG.

5 is a flowchart showing a control operation of a control unit in FIG.

FIG. 6 shows a second local oscillation frequency signal output circuit according to the present invention.
It is a block diagram showing an embodiment of.

7 is a flowchart showing a control operation of the amplifier of the second exemplary embodiment shown in FIG.

FIG. 8 is a third part of the local oscillation frequency signal output circuit according to the present invention.
It is a block diagram showing an embodiment of.

9 is a flowchart showing a control operation of the amplifier of the third exemplary embodiment shown in FIG.

FIG. 10 is a block diagram showing a fourth embodiment of a local oscillation frequency signal output circuit according to the present invention.

11 is a block diagram showing a specific example of a circuit block used in the strong reception electric field in FIG.

12 is a block diagram showing a specific example of a circuit block used when the weak reception electric field in FIG. 10 is used.

13 is a block diagram showing a specific example of the detector shown in FIG.

FIG. 14 is a flowchart showing a specific example of a circuit block switching control operation in the fourth embodiment shown in FIG.

15 is a flowchart showing a specific example of the control operation of the amplifier and the like in the fourth embodiment shown in FIG.

FIG. 16 is a block diagram showing an embodiment of a mobile terminal using a local oscillation frequency signal output circuit according to the present invention.

[Explanation of symbols]

1, 1a, 1b Local oscillator 2, 2a, 2b Balun 3 Frequency divider 4 Phase shifter 5 Gain variable amplifier 6, 7 LNA 8, 9 Mixer 10, 10a to 10d, 10 'Detector 11, 11' Controller 12, 12a, 12b Storage unit 13 Variable gain circuit 14 Fixed gain circuit 15, 16 Changeover switch 17, 17 'Detection circuit 18, 18' Filter 19, 19 'Detection circuit 20 GCA / filter unit 21 A / D conversion unit 22 Modulation Unit 23 error control unit 24 control unit 25 D / A conversion unit 26 storage unit 27 system control unit 28 D / A conversion units 29a and 29b circuit blocks 30a and 30b changeover switch 31 variable gain amplifier 32 multi-phase filters 33 to 35 gain Variable amplifier 36 Multi-phase filters 37, 38 Variable gain amplifier 39 Local buffer section 40 of local oscillation frequency signal output circuit according to the present invention Subband unit 41 Microphone or speaker 42 A / D converter or D / A converter 43 System control unit 44 Voice channel codec 45 Baseband modem 46 D / A converter or A / D converter 47a, 47b Mixer 48 Adder 49 Amplifier 50 BPF ( Band pass filter) 51 Mixer 52 Amplifier 53 BPF 54 Power amplifier 55 Transmission / reception duplexer 56 Transmission / reception antenna 57 Differential converter 58 LPF (low pass filter) 59 Amplifier 60 LPF 61 Amplifier

Continued front page    (72) Inventor Yutaka Igarashi             292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa             Ceremony Hitachi Digital Media Development Book             Department (72) Inventor Akio Yamamoto             292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa             Ceremony Hitachi Digital Media Development Book             Department (72) Inventor Masaki Noda             292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa             Ceremony Hitachi Digital Media Development Book             Department (72) Inventor Kazuaki Hori             Gunma Prefecture Takasaki City Nishi-Yokote-cho 111 Address Co., Ltd.             Hitachi Semiconductor Group Analog Technology Book             Department System Analog Development Department F term (reference) 5K011 DA03 DA06 JA01 KA03

Claims (14)

[Claims] 1. A local oscillation frequency signal output circuit for directly converting a reception signal into a baseband signal, the local oscillator generating an oscillation signal, and a local oscillator having a frequency equal to the reception signal by processing the oscillation signal. A processing unit for generating an oscillation frequency signal, an amplification unit for amplifying the local oscillation frequency signal, a direct conversion unit for converting the received signal into a baseband signal by the local oscillation frequency signal output from the amplifier, A determination unit that determines the level of an interfering wave in the baseband signal obtained by the direct conversion unit, a storage unit that stores reference information for determining the gain adjustment of the amplifier, and a determination unit that determines the determination result. Control for comparing the level of the generated interference signal with the reference information and generating a control signal for adjusting the gain of the amplifier according to the comparison result. DOO has a local oscillation frequency signal output circuit which is characterized in that for adjusting the level of 該局 portion oscillation frequency signal outputted from the amplifying unit according to the level of the interfering signal mixed in the baseband signal. 2. A local oscillation frequency signal output circuit for directly converting a received signal into a baseband signal, the local oscillator generating an oscillation signal and the local oscillation frequency signal generated by shifting the phase of the oscillation signal. A phase converter for converting the local oscillation frequency signal, an amplification unit for amplifying the local oscillation frequency signal, a direct conversion unit for converting the reception signal into a baseband signal by the local oscillation frequency signal output from the amplifier, and the direct conversion unit. A detection unit that detects the level of the baseband signal obtained in step 1, a storage unit that stores reference information for determining the gain adjustment of the amplifier, the detection output of the detection unit, and the reference information. And a control unit for generating a control signal for adjusting the gain of the amplifier according to the comparison result, and the amplification unit according to the detection output of the detection unit. Local oscillation frequency signal output circuit and adjusts the level of 該局 portion oscillation frequency signal outputted from the. 3. The first detection circuit according to claim 2, wherein the detection section detects a level of the baseband signal obtained by the direct conversion section, and a detection output of the first detection circuit interferes with the first detection circuit. A local oscillation frequency signal output circuit comprising a filter for removing a signal and extracting a desired signal, and a second detection circuit for detecting the level of the desired signal output from the filter. 4. The control unit according to claim 3, wherein the control unit obtains a ratio of detection output levels of the first and second detection circuits, compares the level with the reference information stored in the storage unit, and A local oscillation frequency signal output circuit for generating a control signal for adjusting a gain of the amplifier according to a comparison result. 5. A local oscillation frequency signal output circuit for directly converting a received signal into a baseband signal, wherein the local oscillation frequency signal is generated by shifting the phase of the oscillation signal. A phase converter for converting the local oscillation frequency signal, an amplification unit for amplifying the local oscillation frequency signal, a direct conversion unit for converting the reception signal into a baseband signal by the local oscillation frequency signal output from the amplifier, and the direct conversion unit. An A / D converter that converts the baseband signal obtained in step 1 into a digital signal, a demodulator that demodulates the digital signal, an error controller that determines the error rate of the demodulated signal from the demodulator, A control unit for generating a control signal for adjusting the gain of the amplifier according to the error rate determination result, and the amplifier for converting the control signal into an analog signal. A local oscillation frequency signal output circuit for adjusting the level of the local oscillation frequency signal output from the amplification section according to the error rate of the demodulated signal. . 6. A local oscillation frequency signal output circuit for directly converting a received signal into a baseband signal, the local oscillator generating an oscillation signal, and the local oscillation frequency signal generated by shifting the phase of the oscillation signal. A phase conversion section for amplifying the local oscillation frequency signal, a direct conversion section for converting the received signal into a baseband signal by the local oscillation frequency signal output from the amplifier, and a direct conversion section. An A / D conversion unit that converts the obtained baseband signal into a digital signal, a demodulation unit that demodulates the digital signal, processes a transmission / reception signal, and outputs a control signal according to the level of the transmission signal. A system control unit and a D / A conversion unit that converts the control signal into an analog signal and supplies the analog signal to the amplifier are provided. Local oscillation frequency signal output circuit and adjusts the level of 該局 portion oscillation frequency signal outputted from the amplifying unit in response to the bell. 7. A local oscillation frequency signal output circuit for directly converting a received signal into a baseband signal, comprising first and second local oscillators for generating the oscillation signal, and an amplification section for amplifying the oscillation signal. A first circuit block including at least an amplifier and processing the oscillation signal from the first local oscillator to generate a first local oscillation frequency signal; and a second local oscillator including at least an amplifier A second circuit block for processing the oscillating signal from the second local oscillating frequency signal to generate a second local oscillating frequency signal, a changeover switch for selecting one of the first and second local oscillating frequency signals, and the switching A direct conversion unit that converts the received signal into a baseband signal with a local oscillation frequency signal selected by a switch, and the baseband signal obtained by the direct conversion unit. A detection unit for detecting the level of the signal, a storage unit in which a determination reference for switching control of the first and second circuit blocks is stored, a detection output of the detection unit and the determination information are compared. A control unit for generating a first control signal for switching between the first and second circuit blocks according to a comparison result,
A local oscillation frequency signal output circuit, wherein the first and second circuit blocks are switched in accordance with a detection output level of the detection unit. 8. The circuit block according to claim 7, wherein the first and second circuit blocks each include an amplifier, and the control unit controls the first and second circuit blocks according to a level of the baseband signal. A local oscillation frequency signal output circuit for generating a second control signal for gain adjustment of any one of the amplifiers selected by the first control signal. 9. The amplification unit according to claim 1, wherein the amplification unit is a variable gain amplification circuit, and a gain is adjusted by a control signal from the control unit. Local oscillation frequency signal output circuit. 10. The amplifying unit according to claim 1, wherein the amplification unit allows one or more fixed gain amplification circuits that amplify the local oscillation frequency signal and the local oscillation frequency signal to pass therethrough. A local oscillation characterized by comprising a line and a changeover switch for selecting one of these fixed gain amplifier and line, wherein the fixed gain amplifier circuit is in an off state when not selected by the changeover switch. Frequency signal output circuit. 11. The detection unit according to claim 7, wherein the detection unit detects a level of the baseband signal obtained by the direct conversion unit, and a detection output of the first detection circuit. A local oscillation frequency signal output circuit comprising: a filter for removing an interfering signal from the filter and extracting a desired signal; and a second detection circuit for detecting the level of the desired signal output from the filter. 12. The control unit according to claim 11, wherein the control unit generates the first control signal according to a result of comparison between the level of the detection output of the second detection circuit and the determination standard. And a local oscillation frequency signal output circuit. 13. The control unit according to claim 11, wherein the control unit obtains a ratio of detection output levels of the first and second detection circuits and compares the ratio with the reference information stored in the storage unit. A local oscillation frequency signal output circuit for generating a control signal for adjusting the gain of the amplifier according to the comparison result. 14. A mobile terminal having a transmission system and a reception system, wherein transmission and reception are performed by a common antenna, wherein the reception system uses a direct conversion system for directly converting a reception signal into a baseband signal. Used as a means for direct conversion of the received signal,
A mobile terminal using the local oscillation frequency signal output circuit according to any one of claims 1 to 13.