JP2973717B2 - Output level control circuit of high frequency transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output level control circuit for a high-frequency transmission device, and more particularly to a high-frequency transmission device for transmitting a high-frequency signal intermittently, such as a transmission device in a TDMA wireless communication system or a digital cellular mobile telephone system. And an output level control circuit.

[0002]

2. Description of the Related Art An output level control circuit for maintaining the transmission power of a high-frequency transmission device at a predetermined output level includes a high-frequency signal detection circuit (hereinafter referred to as a detection circuit) for detecting a peak value of a high-frequency signal output from a variable amplifier. A comparing section for comparing the output of the detection circuit with a reference voltage corresponding to the predetermined output level, and control means for controlling the output level of the variable amplifying section in response to the output of the comparing section. It has.

[0003] In order to maintain the output level constant over a wide temperature range, the detection circuit needs to detect the high-frequency power level over a wide temperature range with high accuracy. This type of detection circuit described in U.S. Pat. No. 4,523,155 (issued on Jun. 11, 1985) satisfies the above-mentioned requirements. The detection circuit has a detection diode that generates a detection output in response to an envelope of a high-frequency signal, and a temperature compensation element that has substantially the same characteristics as the detection diode and is thermally coupled to the detection diode. And a diode. In this detection circuit, a forward bias voltage is applied from a bias voltage supply point to a detection diode via a bias voltage setting resistor, and the detection output and the bias voltage are superimposed from a load resistor connected to the detection diode. The detection circuit output is obtained. A forward bias voltage is also supplied from the bias voltage supply point to the temperature compensating diode, and the voltage at this bias voltage supply point fluctuates with a change in the forward voltage of the temperature compensating diode. Since the bias voltage of the detection diode is obtained by subtracting the forward voltage of the detection diode from the bias voltage supply point voltage, even if there is a temperature change, it is erased by the temperature change of the forward voltage of the temperature compensation diode. . Therefore, this detection circuit can generate a bias voltage and a detection output that are not affected by a temperature change, that is, a detection circuit output.

The comparison section compares a reference voltage corresponding to a predetermined output level of the intermittent transmission signal with the load voltage, and supplies the comparison output to the control means. The control means controls the gain of the variable amplifier so that the output of the detection circuit matches the reference voltage. When the reference voltage rises or falls, the output of the detector circuit (ie, corresponding to the output level of the transmitted signal) must immediately follow this reference voltage. For example, 800 MH in the EIA system
z CELLULAR SUBSCRIBER UNIT
Recommendations for S (800 MHz Cellular Subscriber Equipment) (EIAINTERIM STANDARD, I
S-19-B, 3.1.3.3, Jan. 1988, U
SA) stipulates that the rise and fall times of the transmission signal be 2 ms or less.

[0005]

However, the output level control circuit of the above-described high-frequency transmission device controls the output level only when the reference voltage exceeds the output of the detection circuit at the time of the rise of the transmission signal. In the case where a bias voltage is applied to the detection diode for temperature compensation as described above, the output level cannot be controlled until the reference voltage becomes higher than the bias voltage of the detection diode. Therefore, at the start of transmission of the transmission power, the output voltage from the detection diode does not change until the reference voltage exceeds the bias voltage, and the rise of the transmission power is delayed for that period, and the reference rise time cannot be satisfied. The problem arises.

In order to solve this problem, there is a method of increasing the control loop gain of the output level control circuit extremely to speed up the rise of the transmission power. In addition to making the loop easy to oscillate, the control loop requires the addition of amplification and filter components.

Accordingly, a first object of the present invention is to provide a high-frequency transmitting apparatus for transmitting an intermittent high-frequency signal at a selected one of a plurality of predetermined output levels at each of the output levels. An object of the present invention is to provide an output level control circuit for a high-frequency transmission device that maintains the output level stably over a temperature range and does not delay the output level from the rise of a reference voltage.

It is a second object of the present invention to provide an output level control circuit of this type in which the number of components constituting the control loop circuit is reduced as much as possible.

[0009]

The output level control circuit of the high-frequency transmission apparatus according to the present invention includes a detection diode and a temperature compensation diode which receive substantially the same bias voltage as in the above-described prior art circuit. A detection circuit that detects a peak value of a high-frequency output from the variable amplification unit, and a comparison unit that compares a detection circuit output corresponding to a detection output of the detection circuit with a reference voltage corresponding to the predetermined output level.
Control means for controlling the output level of the variable amplifying section in response to the output of the comparing section. The output level control circuit further includes a bias voltage detecting means for detecting and storing the bias voltage of the detection diode, and a reference voltage control means for adding the storage bias voltage and an input reference voltage to obtain the reference voltage. And

The reference voltage is obtained by adding the bias voltage of the detection diode to the input reference voltage. When the input reference voltage rises, the reference voltage is always higher than the output voltage of the detection diode (output of the detection circuit). Therefore, the power supply control unit that receives the comparison result of the reference voltage and the output of the detection circuit can provide an effective gain control signal to the variable amplifying unit even at the initial stage of the application of the input reference voltage, so that the transmission output and the output of the detection circuit output rise. Does not delay the change of the input reference voltage. Note that the output of the comparison unit follows the input reference voltage even when the input reference voltage falls, in the same manner as when the input reference voltage rises.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, that is, an example of a high-frequency transmitter for intermittent transmission adapted to a TDMA communication system and a digital cellular mobile telephone system. 2 is a rising waveform diagram of each signal of the transmitter of FIG. 1, (a) is a transmission output signal Po, (b) is an output voltage A of a detection diode, (c) is a reference voltage. The rising waveforms of E and G are shown.

Referring to FIG. 1, a high-frequency transmission device that intermittently outputs a radio-frequency transmission output signal Po includes a transmission signal generator 1 that is controlled by a transmission controller 9 to generate a burst-like input signal Pi. A variable amplifier 2 that amplifies the input signal Pi to generate an amplified signal Pa;
And a detection circuit 3 for guiding most of the signals to the signal output terminal 4 to generate the transmission output signal Po. The supply timing of the input signal Pi is controlled by the transmission control signal H from the transmission control unit 9. The detection circuit 3 also supplies a part Pb of the amplified signal Pa to the detection diode 32 via the coupler 31. The detection diode 32 corresponds to the peak value of the coupler output signal Pb to the load resistor 33 (that is, the transmission peak value). Output signal P
(corresponding to the peak value of o). In addition,
The detection circuit 3 further has a compensation diode 39 having substantially the same temperature characteristics as the detection diode 32. The detection diode 32 and the compensation diode 39 receive a bias voltage having substantially the same value, and the bias voltage fluctuation of the detection diode 32 caused by the temperature fluctuation of the forward voltage is subtracted by the bias voltage fluctuation of the compensation diode 39. Connected. Therefore, the detection circuit output A appearing at the load resistor 33 of the detection diode 32 includes the detection output corresponding to the transmission output signal Po and the fixed bias voltage A0 in which the temperature fluctuation is compensated. The detection circuit output A from the detection circuit 3 is supplied to a minus input terminal of the operational amplifier 6 and compared with a reference voltage E supplied to a plus input terminal of the operational amplifier 6. The comparison output voltage D from the operational amplifier 6 is supplied to the power control unit 5. The power control unit 5 controls the comparison output voltage D
, A control signal C, that is, a voltage obtained by lowering the power supply voltage F in accordance with the magnitude of the comparison output voltage D from the power supply voltage F of the power supply input terminal 8 is generated.
Is supplied to the control signal input terminal 23. In response to the control signal C, the variable amplifying unit 2 controls the power supply voltage of the amplifying element, here the drain voltage of a field-effect transistor (hereinafter referred to as FET). The amplification gain is changed so as to generate the output signal Po.

The transmission signal generating circuit 1 and the variable amplifier 2 described above
The detection circuit 3, the operational amplifier 6, the power control unit 5, and the transmission control unit 9 have the same functions as the output level control circuit of the high-frequency transmission device according to the related art. On the other hand, the output level control circuit according to the present invention includes the load resistor 3 of the detection diode 32 when the input signal Pi is not input, in addition to the above-described components.
3 further includes a reference voltage control unit 7 having a bias voltage detecting unit for storing the temperature-compensated bias voltage A0 generated in 3 and a reference voltage adding unit for superimposing the stored bias voltage A0 and the input reference voltage G. The reference voltage G is supplied from the transmission control unit 9 in synchronization with the transmission control signal H, and therefore in synchronization with the input signal Pi.

Referring to FIG. 1 and FIG. 2, this high-frequency transmission device is in the OFF period of the transmission output signal Po from time T0 to T1, and the reference voltage G synchronized with the input signal Pi is not supplied. At this time, the detection diode 3
2 does not detect the coupler output signal Pb,
2 is approximately equal to the fixed bias voltage A0. The fixed bias voltage A0 of the transmission output signal Po during the OFF period is stored in the bias voltage detecting means of the reference voltage control unit 7, and the stored bias voltage A0 is supplied to the reference voltage adding means of the control unit 7. . Here, since the ON / OFF period of the input signal Pi matches the ON / OFF period of the reference voltage G, the reference voltage control unit 7 refers to the reference voltage G and stores the input timing of the bias voltage A0 to be stored. To determine. At time T1, the input signal Pi is supplied from the transmission signal generation circuit 1 to the variable amplification unit 2, and the reference voltage G is supplied from the transmission control unit 9 to the reference voltage control unit 7, respectively. Since the transmission output signal Po needs to rise to the specified power within 2 milliseconds, the reference voltage G also changes from time T1 to time T3.
It rises with the waveform set within 2 ms.
The reference voltage control unit 7 adds the storage bias voltage A0 and the reference voltage G to obtain a reference voltage E of the output level control circuit. The reference voltage E is supplied to a negative input terminal of the operational amplifier 6. From the time T1 to the time T3, the detection circuit output voltage A is lower than the reference voltage E, and the gain control of the variable amplifier 2 by the power supply controller 5 is activated. As a result, the power level of the transmission output signal Po and the detection diode 32
The detection circuit output A immediately follows the reference voltage E at time T
When it reaches 3, the transmission output signal Po reaches a predetermined output corresponding to the reference voltage E.

Instead of performing the above-described reference voltage processing by the bias voltage detecting means and the reference voltage adding means of the reference voltage control section 7, the input reference voltage G is directly supplied to the operational amplifier 6 as in the prior art (FIG. 2). (C), and the output voltage A1 of the detection diode 32 (see FIG. 2 (b)) rises with a delay of the time t from the reference voltage G, and accordingly, the rise of the transmission output signal Po1 also delays with the time t (see FIG. 2C). FIG. 2A). In the transmission level control circuit according to the prior art, the time t is about 1 millisecond, and it is difficult to make the rise time of the transmission output signal Po1 shorter than a prescribed rise time (2 milliseconds). However, in this embodiment, since the rise delay time t can be made substantially zero, it is easy to make the rise time (T3-T1) within 2 milliseconds.

Further, referring to FIG. 1, the high-frequency transmitting apparatus has a maximum output power level of a transmission output signal Po of 0.6 W and outputs one of a plurality of output power levels having an equal difference of 4 dB. You can select and send it arbitrarily.

The variable amplifying section 2 is an amplifier including an FET as an amplifying element, and receives an input signal P from a signal input terminal 21.
i is amplified by this FET, and an amplified signal Pa is output from the signal output terminal 22. The control signal C from the power control unit 5 is
The signal is input to the control signal input terminal 23 of the variable amplifier 2,
The drain voltage of the FET is controlled, and the gain of the variable amplifier 2 is controlled by the drain voltage control.

Still referring to FIG. 1, the detection circuit 3
The coupling end of the coupler 31 is connected to the anode of the detection diode 32, the cathode of the diode 32 is connected to the detection voltage output terminal 41, and the detection voltage output terminal 41 outputs the detection circuit output A. A load resistor 33 of the diode 32 and a capacitor 34 forming a bypass circuit for a high frequency signal are connected in parallel between the cathode of the diode 32 and the ground potential point. The insulated end of the coupler 31 is connected to a series circuit of a terminating resistor 35 and a capacitor 36 for bypassing a high frequency signal, and this series circuit is connected to the amplified signal Pa.
Termination circuit. A bias voltage Vbb is supplied from a bias voltage input terminal 40. The bias voltage Vbb applies a forward bias voltage to the anode of a compensation diode 39 whose cathode is grounded via a series circuit of resistors 37 and 38. The connection point between the resistors 37 and 38 is further commonly connected to the connection point (point B) between the resistor 35 and the capacitor 36, and also applies a bias voltage A0 substantially equal to the bias voltage of the compensation diode 39 to the detection diode 32. The voltage at the bias voltage supply point B is determined mainly by the compensation diode 39 and the circuit on the resistor 38 side.

[0020] In the no-input of the amplified signal Pa, the bias voltage A0 of the load voltage generated in the detection voltage output terminal 41, i.e. resistor 33, i.e. the diode 32, (a voltage V _B) the common connection point voltage B Than the forward voltage Vf of the diode 32. When the forward voltage Vf of the diodes 32 and 39 fluctuates with the temperature fluctuation, the diodes 32 and 3 correspond to the fluctuation of the forward voltage Vf.
Voltage V _B of the bias voltage supply point B to 9 also varies by the same voltage. Therefore, the temperature fluctuation of the forward voltage Vf due to the diodes 32 and 39 is offset, and the voltage A0 generated at the detection voltage output terminal 41 does not substantially fluctuate. Next, when the amplified signal Pa is applied to the detection circuit 3, the detection diode 32
This coupler output signal Pb is detected and the bias voltage A0 is detected.
The output A of the detection circuit obtained by adding the detection output to the load resistor 33,
That is, it occurs at the detection voltage output terminal 41.

FIG. 3 is a partial circuit diagram of FIG.

Referring to FIG. 3, power supply control unit 5 includes
The power supply voltage F from the power supply input terminal 8 is applied to the emitter of the transistor 51, and the transistor 51 generates a control signal C at the collector of the power supply voltage F, which is reduced according to the base current. The comparison output voltage D from the operational amplifier 6 is supplied to the base of the transistor 53, and the transistor 53 generates a collector current corresponding to the comparison output voltage D. The collector current of the transistor 53 is connected to the resistor 5
The current is supplied to the base of the transistor 51 via the reference numeral 2 and becomes the base current. When the base current of the transistor 51 increases, the voltage drop due to the transistor 51 decreases, so that the voltage of the control signal C supplied to the drain terminal of the FET built in the variable amplifier 2 increases, and the gain of the variable amplifier 2 increases. Therefore, when the detection circuit output A is smaller than the reference voltage E, the comparison output voltage D from the operational amplifier 6 increases, and the increase of the comparison output voltage D increases the gain of the variable amplifier 2. The increase in the gain of the variable amplifying section 2 increases the output A of the detection circuit until the output A matches the reference voltage E.

FIG. 4 is a circuit diagram of another part of FIG.

Referring to FIG. 4, this reference voltage control unit 7
Performs digital signal processing in response to an analog detection circuit output A from the detection circuit 3 and a digital reference voltage G from the transmission control unit 9, and converts the signal-processed analog reference voltage E to the operational amplifier 6. Supply to + terminal. The output A of the detection circuit is converted into a digital signal by an analog-digital (A / D) converter 72, and this digital signal is input to a controller (CONT) 73. This digital signal is sampled by the controller 73 every input suspension period of the reference voltage G. This sampled digital signal is stored in the memory 75 and updated. The digital signal stored in the memory 75 is
Of the bias voltage A0. On the other hand, the reference voltage G
Is directly input to the controller 73. When the reference voltage G is input, the controller 73 adds the reference voltage G and the digital signal stored in the memory 75, and supplies the added output to the digital-analog (D / A) converter 71. I do. The D / A 71 converts the added output into an analog reference voltage E, and supplies the reference voltage E to the + terminal of the operational amplifier 6.

When it is not necessary to set the bias voltage A0 with high accuracy, it is not necessary to update the digital signal every time the reference voltage G is stopped, and the bias voltage A0 obtained by an experiment or the like is read-only in advance. May be stored in the memory 74.

The reference voltage G and the bias voltage A0 may be stored in the memory 74 in advance, and the transmission control unit 9 may input the transmission timing signal J synchronized with the input signal Pi to the controller 73. The controller 73 reads the reference voltage G and the bias voltage A0 from the memory 74 and adds them in synchronization with the timing signal J, and supplies the added signal to the D / A 71.

[0027]

As described above, the output level control circuit of the high-frequency transmission device according to the present invention adds the bias voltage of the detection diode and the input reference voltage to create a new reference voltage, and thereby outputs the transmission output signal. The power level is maintained stably over a wide temperature range, and the output power level is controlled so as not to be delayed from the rise of the input reference voltage. Further, the output level control circuit described above does not need to form a special control loop, so that the number of circuit components can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an example of a high-frequency transmitter for intermittent transmission adapted to an embodiment of the present invention, that is, a TDMA communication system or a digital cellular mobile telephone system.

FIG. 2 is a rising waveform diagram of each signal of the transmitter of FIG. 1; (A) shows the transmission output signal Po, (b) shows the output voltage A of the detection diode, and (c) shows the rising waveform of the reference voltages E and G.

FIG. 3 is a partial circuit diagram of FIG. 1;

FIG. 4 is a block diagram of another part of FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transmission signal generation circuit 2 variable amplification unit 3 detection circuit 4 signal output terminal 5 power supply control unit 6 operational amplifier 7 reference voltage control unit 8 power supply input terminal 9 transmission control unit 21 signal input terminal 22 signal output terminal 23 control signal input terminal 31 Coupler 32 Detection diode 33, 35, 37, 38 Resistor 34, 36 Capacitor 39 Compensation diode 40 Bias voltage input terminal 41 Detection voltage output terminal 51, 53 Transistor 52 Resistor 71 Digital-analog converter (D / A) 72 Analog -Digital converter (A / D) 73 Controller (CONT) 74, 75 Memory

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-62741 (JP, A) JP-A-2-272921 (JP, A) JP-A-2-260709 (JP, A) JP-A-2- 217011 (JP, A) JP-A-2-65305 (JP, A) JP-A-64-61178 (JP, A) JP-A-60-22830 (JP, A) JP-A-62-181029 (JP, U) 60-119122 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H03G 3/20 H03F 1/30 H03F 3/19 H03F 3/24

Claims (13)

(57) [Claims] 1. A burst-like transmission according to a first control signal.
A transmission signal generating means for generating a signal, the transmission signal first
A variable amplifying means for amplifying with a gain corresponding to the control signal of No. 2 to generate an amplified signal, a detecting means for detecting a power level of the amplified signal by a detecting diode to which a bias voltage is applied, a reference voltage and a detecting means for the detecting means. Control means for generating the second control signal for causing the variable amplifying means to generate an amplified signal having a level corresponding to the reference voltage in response to a detection means output voltage obtained by adding an output voltage to the bias voltage. The output level control circuit of the transmitting device
The output level control circuit further includes the first control signal.
A reference voltage control means for adding the bias voltage of the detection diode to the input reference voltage supplied during the ON period of the transmission signal in synchronization with the signal, and generating the reference voltage. Control circuit. 2. The apparatus according to claim 1, wherein the detection unit includes a coupler that supplies a part of the amplified signal to the detection diode, and a bias unit that keeps the bias voltage of the detection diode substantially constant regardless of a temperature change. 2. The output level control circuit according to claim 1, wherein the output level control circuit includes: 3. The biasing means includes a compensation diode having an anode connected to a bias voltage supply point via a first resistor and a cathode grounded, and having the anode of the detection diode connected to a second resistor and the coupler. 3. The high-frequency transmission according to claim 2, wherein the high-frequency transmission is connected to the bias voltage supply point via a power supply, and the cathode of the detection diode is connected to a resistor constituting an output terminal of the bias voltage and the detection means output voltage. The output level control circuit of the device. 4. A comparison means for comparing the reference voltage with an output voltage from the detection means, and a power supply control means for generating the second control signal in response to the output voltage of the comparison means. 3. The output level control circuit according to claim 2, comprising: 5. A power supply control means, comprising: a first transistor receiving the output of the comparison means as a base and having an emitter grounded; and a base connected to a collector of the first transistor via a resistor and connecting the collector to the first transistor . 5. The output level control circuit according to claim 4, further comprising a second transistor having an output terminal for the second control signal and a second transistor having an emitter as an input terminal of a power supply. 6. The high-frequency transmission device according to claim 5, wherein said variable amplification means includes a field-effect transistor as an amplifying element of said transmission signal, and said control signal controls a drain voltage of said field-effect transistor. Output level control circuit. Wherein said reference voltage control means comprises: a bias voltage detecting means for storing the bias voltage of the detection diode in the OFF period of the transmission signal, the reference voltage by adding the stored bias voltage to said input reference voltage output level control circuit of the high frequency transmission apparatus according to claim 1 or 2 wherein, characterized in that it comprises a reference voltage adding means for causing. Wherein said reference voltage control means, analog-converts the detection means output voltage to a digital signal - digital conversion means, a memory means for storing the bias voltage of the detecting diode of said digital signal, said Controller means for controlling the analog-to-digital conversion means and the memory means and adding the storage bias voltage to the input reference voltage in digital form to produce no added output; and a digital-analog for converting the added output to an analog signal. output level control circuit of the high frequency transmission apparatus according to claim 1 or 2 wherein, characterized in that it comprises a conversion means. 9. The reference voltage control means includes : a memory means for storing a preset bias voltage of the detection diode; and a controller means for adding the storage bias voltage to the digital input reference voltage to generate an added output. When digital converting the sum output to the reference voltage of the analog form - output level control circuit of the high frequency transmission apparatus according to claim 1 or 2 wherein, characterized in that it comprises an analog conversion means. 10. The reference voltage control means includes : a memory for storing a preset bias voltage of the detection diode and the input reference voltage;
Controller means for adding the storage bias voltage and the storage input reference voltage in synchronism with the N state to generate an addition output; and digital-analog conversion means for converting the addition output to the analog reference voltage. output level control circuit of the high frequency transmission apparatus according to claim 1 or 2, wherein the. 11. A burst-like transmission according to a first control signal.
Transmission signal generation means for generating a transmission signal , variable amplification means for amplifying the transmission signal by a field-effect transistor under the control of the drain voltage, and a coupler for demultiplexing a part of the transmission signal from the variable amplification means, A detection diode that outputs a sum output voltage of a detection output corresponding to the power level of the divided transmission signal and the applied bias voltage to a load resistor, and a bias voltage of the detection diode substantially regardless of temperature fluctuation. Detecting means including bias means for keeping the voltage constant; comparing means for comparing a reference voltage with the added output voltage; and a second control means for controlling a drain voltage of the field effect transistor in response to an output of the comparing means. power control means for generating a control signal;
A high-frequency transmitting apparatus comprising: a reference voltage control unit that generates a reference voltage by adding a bias voltage of the detection diode to an input reference voltage supplied when the transmission signal is in an ON state in synchronization with the transmission signal. Output level control circuit. 12. The reference voltage control unit includes : a bias voltage detection unit configured to store a bias voltage of a detection diode of the detection unit in an OFF state of the transmission signal; and a memory configured to add the storage bias voltage to the input reference voltage. The output level control circuit according to claim 11, further comprising: a reference voltage adding unit that generates the reference voltage. Wherein said reference voltage control means, analog-converts the sum output voltage into a first digital signal - digital conversion means, a bias voltage of the detector diode which constitutes a part of the first digital signal Memory means for storing a corresponding second digital signal, and controller means for controlling the analog-to-digital conversion means and the memory means and for adding the storage bias voltage to the input reference voltage in digital form to produce an added output When,
12. The output level control circuit according to claim 11, further comprising: a digital-to-analog conversion unit that converts the added output to the reference voltage.