JPS61214825A - High frequency power amplifying circuit - Google Patents

Abstract

PURPOSE:To reduce the spread of a spectrum for burst switching by connecting a silicon diode and a PIN diode in series between the input terminal of an input high frequency signal and the output terminal of an attenuated high frequency signal. CONSTITUTION:In an input level control circuit 1, a point contacting silicon diode 6 and PIN diodes 7 of two stages are connected in series between an input terminal 31 and an output terminal 32. Since PIN diodes 7 are controlled from the turn-on state to the state approximating the turn-off state by a level control signal 104 from a comparing circuit 4, a high power high frequency signal of an envelope waveform has not the spectrum spread and has smooth rise and fall waveforms, and the dynamic range of the ratio of the output for burst turn-on that for burst turn-off is taken sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high-frequency power amplification circuit used in a transmitter or the like in rural communication between TDMA communication ground stations.

(Prior Art) FIG. 8 is a block diagram of a conventional high frequency power amplifier circuit of this type. This power amplifier circuit controls the output waveform in order to prevent the spectrum of the transmission output signal from expanding to the extent that it adversely affects other transmission channels or the reception channel of the own station due to burst switching. In an output with little spectral spread, the envelope curve has gentle rises and falls, and FIG. 7 shows an example of such a preferable envelope curve. In the high frequency power amplifier circuit shown in FIG. 8, the λ level control circuit 10 attenuates the input high frequency signal 121 according to the level control signal 104, and outputs an attenuated high frequency signal 110. The amplifier 2 attenuates the high frequency signal 11
0 is power amplified and a high power high frequency signal 102 is output.

The detector 3 performs envelope detection of the high power high frequency signal 102,
An envelope signal 103 is output. The reference envelope signal generating circuit 5 generates a DC reference envelope signal 105 having a positive half or a negative half of the waveform shown in FIG. Reference envelope signal 1
05 is a waveform desired as the envelope signal 103. The comparison circuit 4 outputs an envelope signal 103 and a reference envelope signal 105.
A level control signal 104 having a waveform of a radio wave difference between the two and the same is output.

Level control signal 104 represents the error of envelope signal 103 relative to reference envelope signal 105. The circuit in Figure 8 is
In this way, a closed loop is constructed, and the high power high frequency signal 102
The waveform of the reference envelope signal 105 is similar to the waveform of the reference envelope signal 105.

FIG. 9 is a circuit diagram of the input level control circuit 10. As shown in this figure, the conventional input level control circuit has two pin diodes 15 between an input terminal 31 and an output terminal 32.
In the circuit shown in the figure, in which the pin diode 15 is connected in series, the pin diode 15 does not turn on until it reaches a certain bias value, and suddenly turns on when it reaches a certain bias value, as shown in the characteristic diagram in Figure 3. It has hysteresis to turn on.

Therefore, input high frequency signal 1 to input level control circuit 10
21 enters the hysteresis region, the pin diode 15 suddenly turns on and the input level to the power amplifier 2 rapidly increases, so the waveform of the output 102 of the power amplifier 2 becomes a high-power, high-frequency waveform as shown in FIG. The rising waveform of the envelope of the signal 102 becomes steep, and as a result, the spectrum of the output 102 expands.

(Problem to be Solved by the Invention) Conventionally, in order to suppress the spread of this spectrum, the level of the control signal 104 was adjusted to avoid the hysteresis region, but since the pin diode 15 could not be completely turned off, The envelope of the high power high frequency signal 102 has a waveform as shown in FIG. Therefore, in conventional circuits, it was not possible to maintain a dynamic range of the carrier leak ratio during burst-on and burst-off. As described above, the conventional high frequency power amplifier circuit has a problem in that the spectrum spreads greatly during burst switching of the high frequency signal.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a high-frequency power amplifier circuit in which the spectrum spread is small during burst switching of high-frequency signals.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides an input level control system that applies attenuation to an input high frequency signal according to a level control signal and outputs an attenuated high frequency signal. a circuit, an amplifier that amplifies this attenuated high frequency signal and outputs a high power high frequency signal, a detector that detects this high power high frequency signal and outputs an envelope signal of the high power high frequency signal, and the envelope signal. A high frequency power amplification circuit comprising: a circuit for generating a reference envelope signal representing a desired envelope; and a comparison circuit for generating the level control signal representing a difference in waveform between the envelope signal and the reference envelope signal. The input level control circuit is characterized in that it includes a silicon diode and a pin diode connected in series between an input terminal for the input high frequency signal and an output terminal for the attenuated high frequency signal.

(Example) Next, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. In this embodiment, the input 101 to the power amplifier 2 is controlled by the input level control circuit 1 in accordance with the reference envelope signal 105 having gentle rising and falling waveforms generated by the reference envelope signal generating circuit 5, and 2
The output 102 of the detector 3 is subjected to envelope detection, and the output 103 of the detector 3 is compared with the output 105 of the reference envelope signal generation circuit 5 by the comparison circuit 4, and the error signals of both are used as the level control signal 104. Input level control circuit 1
The envelope waveform of the output signal 102 of the power amplifier 2 is controlled to be similar to the output signal 105 of the reference envelope signal generation circuit 5, thereby forming a closed loop in which the output signal 102 of the power amplifier 2 is input to The spread of the spectrum of the output 102 is suppressed.

The input level control circuit 1 in this embodiment includes point contact type silicon diodes 6 and 2, as shown in the circuit diagram in FIG.
The stage pin diode 7 and the input terminal 31 and output terminal 32
By adding a point contact type silicon diode 6, compared to the conventional input level control circuit 10 consisting of two stages of pin diodes, the characteristics shown in FIG. As shown in the figure, hysteresis has been significantly reduced.

In this way, if this embodiment is used, the level control signal 104 from the comparator circuit 4 can control the pin diode from an on state to a nearly off state, so that the envelope waveform of the high power high frequency signal 102 is as shown in FIG. It will be as shown. 7th
The high-power high-frequency signal 102 with an envelope waveform as shown in the figure has smooth rising and falling waveforms without spectrum expansion, and has a sufficient dynamic range of the output ratio between burst-on and burst-off. There is.

(Effects of the Invention) As explained above, according to the present invention, the high frequency power amplifier circuit has a small spread of the spectrum during burst switching of high frequency signals, and further improves the carrier leak ratio during burst on/off. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a specific example of the input level control circuit in the embodiment of FIG. 1, and FIG. 3 is a control signal of a conventional input level control circuit. Figure 4 is a diagram showing the output level characteristics for the control signal of the input level control circuit in Figure 2. Figures 5 and 6 are the high frequency output of a conventional high frequency power amplifier circuit. A diagram showing an example of the envelope waveform of
7 is a diagram showing an example of the envelope waveform of the high frequency output in the embodiment shown in FIG. 4, FIG. 8 is a block diagram showing an example of a conventional high frequency power amplifier circuit, and FIG. FIG. 2 is a circuit diagram showing an input level control circuit in the high frequency power amplifier circuit of FIG. 1.10... Input level control circuit, 2... Amplifier,
3... Detector, 4... Comparison circuit, 5... Reference envelope signal generation circuit, 6... Silicon diode, 7, 1
5... Bindaode, 8... Control signal application circuit, 9
···coil. Representative Patent Attorney Shinsuke Honjo Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] an input level control circuit that applies attenuation to an input high frequency signal according to a level control signal and outputs an attenuated high frequency signal; an amplifier that amplifies this attenuated high frequency signal and outputs a high power high frequency signal; a detector for detecting and outputting an envelope signal of the high-power high-frequency signal; a circuit for generating a reference envelope signal representing an envelope desired as the envelope signal; and the envelope signal and the reference envelope signal. and a comparator circuit that generates the level control signal representing a difference in waveform between A high frequency power amplification circuit characterized by comprising a silicon diode and a pin diode connected to.