JP2001358600A - Transmission power control circuit for transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission power control circuit which can control the transmission power of a transmitter with high accuracy in a wide dynamic range without exerting any adverse effect upon the ALC characteristic. SOLUTION: A closed loop circuit is constituted of a first error amplifying section 5 which compares an output voltage detected by means of a detecting section 3 with a reference voltage outputted from a reference voltage generator and amplifies the difference between the voltages and a driver section 7. The circuit is also provided with a delay circuit section 14, second and third error amplifying sections 11 and 12, an integration circuit section 13, and an adding section 6. The delay circuit 14 outputs a delayed reference voltage which is delayed by a fixed time lag upon receiving the reference voltage. The second error amplifying section 11 amplifies the difference between the reference voltage and delayed reference voltage. The output voltage of the section 11 is inputted to the third error amplifying section 12 and the output of the section 12 is added to the output voltage of the first error amplifying section 5 in the adding section 6. The output voltage of the second error amplifying section 12 is inputted to the third error amplifying section 12 through the integration circuit section 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission power control circuit used in a wireless transmission device such as a mobile communication device such as a mobile communication device such as a portable wireless device, and more particularly to a microwave / millimeter transmission circuit. The automatic output control circuit (Aut) is used for a transmitter having a variable gain function among waveband transmitters.
omatic Level Control circuit (hereinafter abbreviated as ALC)
And a transmission power control circuit having a closed loop circuit configuration according to (1).

[0002]

2. Description of the Related Art Generally used portable telephones (mobile stations) have a function of controlling their own transmission power according to the distance between a base station and the mobile station. In order to minimize interference, high-precision transmission power control over a wide dynamic range is required.

[0003]

However, at present, in a communication system requiring a wide dynamic range and high-precision transmission power control, it is difficult to realize a high-speed response of the transmission power control without deteriorating the communication quality. is there. For example, in the case of a general ALC circuit, if the reference voltage is changed by 1 dB from the outside, the transmission output changes at a pull-in speed corresponding to the ALC loop band. It takes several tens of msec to reach the desired level.
Output level control at msec / dB cannot be realized. A
If the LC loop band is expanded, a high-speed response of the transmission output is possible, but it is not desirable because the communication quality deteriorates.

An object of the present invention is to provide a transmission power control circuit capable of performing high-precision transmission output control over a wide dynamic range without affecting the ALC characteristics at all.

[0005]

According to the present invention, there is provided a variable gain amplifier for amplifying an input transmission signal, a transmission output detector for detecting an output voltage of the variable gain amplifier, an output of the detected output voltage and a reference voltage generator. Compare the output reference voltage,
A closed loop circuit comprising a first error amplifier for amplifying the difference and a driver, a delay circuit, a second error amplifier, a third error amplifier, an integration circuit, and an adder. The delay circuit receives the reference voltage and outputs a delayed reference voltage delayed by a predetermined delay time, and the second error amplifying unit outputs a difference between the reference voltage and the delayed reference voltage. The output voltage from the second error amplifier is input to a third error amplifier, and the output of the third error amplifier is added to the output voltage of the first error amplifier by the adder. The output voltage of the error amplifying unit is input to the third error amplifying unit through the integration circuit unit, thereby obtaining a transmission power control circuit of the transmitter.

Further, according to the present invention, a closed loop circuit is configured such that the reference voltage input from the reference voltage generator is controlled to obtain an output power corresponding to the reference voltage. A transmission power control circuit of the transmitter is obtained.

Further, according to the present invention, when the reference voltage is constant, the output voltage of the delay circuit section matches the reference voltage, and when the reference voltage is changed, the current reference voltage and the current reference voltage are changed. The difference of the delay circuit is amplified by the second error amplifier, and
3. The transmission power control circuit for a transmitter according to claim 1, wherein the addition is performed by the addition unit from outside the closed loop circuit without passing through the first error amplification unit through the error amplification unit. Can be

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the transmission power control circuit of the present invention will be described below in detail. The configuration of the transmission power control circuit includes a variable gain amplifying unit 1, a branching unit 2, a detecting unit 3,
Logarithmic amplifier 4, first error amplifier (hereinafter referred to as loop amplifier) 5, adder 6, driver 7, second error amplifier 11, third error amplifier 12, integration circuit 13,
And a delay circuit section 14.

A high-frequency signal is input from an input terminal 101 and output from an output terminal 102. An output power setting voltage (hereinafter, referred to as a reference voltage) is input from a reference voltage input terminal 111. The detection voltage of the output power is output from the logarithmic amplifier 4, compared with a reference voltage by the loop amplifier 5, and input to the variable gain amplifier 1 via the driver 7 to form an ALC circuit.

The reference voltage is also supplied to the delay circuit 1
4, the third error amplifier 1 through the second error amplifier 11
2 and its output is added by an adder 6 to a loop amplifier 5
Is added to the output voltage. The output voltage of the third error amplifier 12 is also input to the third error amplifier 12 through the integration circuit 13.

Hereinafter, the operation of the transmission power control circuit of the present invention will be described. In the present embodiment, an ALC circuit configured to obtain an output power according to the reference voltage by controlling a reference voltage input from the reference voltage input terminal 111 is configured.

The delay circuit section 14 outputs a reference voltage at a past point in time for a fixed delay time. When the reference voltage is constant, the output voltage of the delay circuit unit 14 matches the reference voltage. Second error amplifier 11, third
The output voltage of the error amplifier 12 is ideally 0V.

When the reference voltage is changed, the difference between the current reference voltage and the delay circuit 14 is amplified by the second error amplifier 11, and the ALC loop is passed through the third error amplifier 12 without passing through the loop amplifier 5. Are added by the adding unit 6 from outside.

The low frequency components of the output offset voltages of the third error amplifier 12 and the second error amplifier 11 generated by disturbance such as a change in environmental temperature are suppressed by the integration circuit 13. Thus, when the reference voltage is constant, the output voltage of the third error amplifier 12 is always constant and does not change. Since the integration circuit section 13 does not act on high-frequency components, the second
The error amplifier 11 and the third error amplifier 12 follow and the output voltage of the third error amplifier 12 changes.

Hereinafter, the effect when the circuit having the above configuration operates as described above will be described. As an example, the effect will be described using a transmission unit of a microwave communication device having a signal transmission speed of several tens to several hundreds Mbps. Output power variable speed 10ms
Assume that ec / dB is needed.

In general, the transmission ALC loop band of a communication device having such a transmission speed needs to be selected to be about several tens Hz or less. This is because a low frequency component of the modulation signal is removed by the ALC loop and communication quality represented by a bit error rate is degraded. Here, the ALC loop band is 10H
Description will be made as z.

Consider a case where the transmission output power is changed by 1 dB from the steady state in this system. In the case of a general ALC circuit without the circuit of the present invention, when the reference voltage is changed by 1 dB from the outside, the transmission output changes at a pull-in speed corresponding to the ALC loop band. Since it takes several tens of msec to reach the desired level,
Output level control at 10 msec / dB cannot be realized. If the ALC loop band is widened, a high-speed response of the transmission output is possible, but it is not desirable because the communication quality is deteriorated.

On the other hand, in the circuit of the present invention, the second error amplifier 11, the third error amplifier 12, and the integration circuit 1
3. The circuit portion constituted by the delay circuit section 14 is AL
Not included in the closed loop circuit of the C loop. Therefore, this part has a circuit configuration that does not affect the ALC loop band. Also, in this part, a high-speed response is possible because only the delay circuit unit 14 needs to have a time constant much smaller than the ALC loop band.

When the reference voltage is changed by an amount corresponding to 1 dB from the outside, the second voltage is changed according to the change in the reference voltage.
, The output voltage of the error amplifier 11 changes, and the input voltage of the driver 7 is forcibly changed without being restricted by the time constant determined by the ALC loop. As a result, the gain changes and the transmission output is set to a desired level at a high speed. Of course, it is also possible to have a certain time constant in order to suppress the overshoot of the transmission output.

Since this circuit portion constituted by the third error amplifier 12 and the like is outside the ALC loop, generation of an offset voltage due to temperature characteristics or the like in this portion cannot be suppressed in the ALC loop. is there. However, the circuit of the present invention does not generate an offset voltage in principle. The generated offset voltage is passed through the integration circuit 13 to the third error amplifier 12
In the steady state where the reference voltage is constant, the output voltage of the third error amplifier 12 is 0 V in principle. The low frequency component, that is, the DC component is always 0 V, and does not change even when the environmental temperature changes. Therefore, the circuit portion of the present invention constituted by the third error amplifying unit 12 and the like is equivalent to no circuit connection under a constant reference voltage, and does not affect the ALC characteristics at all.

In a system in which the transmission output control width is several tens of dB, the control voltage of the variable gain amplifying unit 1, that is, the input voltage of the driver unit 7 is also in a wide voltage range. Although the voltage affects the transmission output accuracy, the circuit according to the present invention can ignore the effect, thereby enabling high-precision transmission output control over a wide dynamic range.

On the other hand, when the reference voltage is changed, the output voltage of the second error amplifier 11 changes, and the output voltage of the third error amplifier 12 also changes at high speed. Since the integrator 13 does not respond to a voltage change faster than the time constant of the integrator 13, no feedback is applied to the third error amplifier 12.

Next, another embodiment of the transmission power control circuit of the present invention will be described with reference to FIGS. FIG.
Is an example in which the detector 3 and the logarithmic amplifier 4 in FIG.
This is a case where the SI detector 20 is used, and in this case, the same effect as in the case of FIG. 1 described above can be obtained.

FIG. 3 shows an embodiment in which a mixer 21 and a local oscillator 22 are used in a stage preceding the detector 3 in FIG.
This is an embodiment in the case where down-conversion is performed to a frequency band in which the I detector 20 can directly operate. In this case, the same effect as in the case of FIG. 1 can be obtained.

FIG. 4 shows an embodiment in which the logarithmic amplifier 4 of FIG. 1 is omitted.

[0026]

As described above, according to the present invention, a transmission output control circuit having a wide dynamic range and high accuracy capable of setting a high-speed output level without affecting the ALC loop band can be realized. Therefore, it is possible to realize a transmitter having a wide transmission output power control range and excellent transmission output accuracy, and realizing a high-speed variable transmission output power level without deteriorating communication quality.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

FIG. 3 is a block diagram showing still another embodiment of the present invention.

FIG. 4 is a block diagram showing still another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 variable gain amplifying unit 2 branching unit 3 detecting unit 4 logarithmic amplifying unit 5 first error amplifying unit (loop amplifier unit) 6 adding unit 7 driver unit 11 second error amplifying unit 12 third error amplifying unit 13 integrating circuit Unit 14 delay circuit unit 20 RSSI detector 21 mixer unit 22 local oscillator 101 input terminal 102 output terminal 111 reference voltage input terminal

Claims (7)

[Claims] 1. A variable gain amplifying unit for amplifying an input transmission signal, a transmission output detecting unit for detecting an output voltage thereof, and comparing the detected output voltage with a reference voltage output from a reference voltage generator. A first error amplifier for amplifying the difference, a closed loop circuit including a driver, a delay circuit, a second error amplifier, and a third error amplifier;
The delay circuit receives the reference voltage and outputs a delayed reference voltage delayed by a predetermined delay time, and the second error amplifier includes the reference circuit. The difference between the voltage and the delayed reference voltage is amplified. The output voltage from the second error amplifier is input to the third error amplifier, and the output is output from the first error amplifier by the adder. A transmission power control circuit for a transmitter, wherein an output voltage of the third error amplifier is added to the third error amplifier through the integration circuit. 2. The closed loop circuit according to claim 1, wherein said reference voltage input from said reference voltage generator is controlled to obtain an output power corresponding to said reference voltage. Transmit power control circuit of the transmitter. 3. When the reference voltage is constant, the output voltage of the delay circuit unit matches the reference voltage. When the reference voltage is changed, the difference between the current reference voltage and the delay circuit unit is calculated. The second
3. The signal is amplified by an error amplifying unit, and added by the adding unit from outside the closed loop circuit without passing through the first error amplifying unit through the third error amplifying unit. A transmission power control circuit of the transmitter as described in the above. 4. The transmission power control circuit for a transmitter according to claim 1, wherein said transmission output detection section comprises a detection section and a logarithmic amplification section. 5. The transmission power control circuit according to claim 1, wherein the transmission output detection unit is an RSSI detector. 6. The transmission power control circuit for a transmitter according to claim 1, wherein said transmission output detection section comprises a mixer section, a local oscillator, and an RSSI detector. 7. The transmission power control circuit for a transmitter according to claim 1, wherein said transmission output detection section comprises only a detection section.