JPS60217705A - Power amplifier - Google Patents

Abstract

PURPOSE:To keep the reliability by detecting an input pulse signal, generating a drain voltage of an FET to be in an optimum state to attain low power consumption and keep an average channel temperature of the FET constant. CONSTITUTION:A high frequency input signal inputted from an input terminal 12 is divided into two by a distributor 16. The repetitive rate of a pulse and pulse width of the signal detected by a detector 17 are detected by a detection circuit 18, an optimum drain voltage making the average channel temperature constant is generated by the input from a detection circuit 18 and a prescribed data stored in a signal generating circuit 19, the signal is converted into a pulse by a control circuit 20 and a pulse form of the optimum drain voltage is applied to the FET of an amplifier 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a power amplifier, and particularly to a power amplifier using a high-output transistor as an amplifying element.

(Prior Art) Recently, many high-output, high-frequency transistors have been developed, and their applications are being studied. Among these transistors, GaAs field effect transistors (hereinafter referred to as FE)
T) can be said to be the most suitable amplification element for high output and high frequency. FIG. 1 shows a conventional power amplifier circuit in which multiple stages of FETs are connected in cascade. In the figure, FETIs each always biased at a constant voltage value from a gate voltage terminal 4 and a drain voltage terminal 5 are connected in cascade in multiple stages.
A high frequency signal is input to the input terminal 2 of the first stage power amplifier, multi-stage amplified to a desired level, and output from the output terminal 3.

In such conventional power amplifiers, the gate and drain currents of each FB'I' remain constant even when the high-frequency input signal is a pulse, so DC power is wasted even when there is no high-frequency input signal. However, it had the disadvantage of low power usage efficiency. On the other hand, in synchronization with the pulse of the high frequency input signal, the gate voltage and drain voltage of the FET are turned ON10.
The power consumption of the power amplifier can be improved by supplying power to the gate voltage terminal 4 and the drain voltage terminal 5 in such a manner that the gate voltage terminal 4 and the drain voltage terminal 5 are FF. However, in this case as well, if the drain voltage is increased to the rated value and a large peak drain current is passed in order to increase the output power of the power amplifier, each FE
The average channel temperature of T can rise near the rated temperature in the trench due to ambient temperature.

In such a power amplifier, when the repetition rate of the input pulse increases or the pulse width becomes wider, the above-mentioned average channel temperature further increases, resulting in a decrease in the reliability of the power amplifier.

(Objective of the Invention) An object of the present invention is to eliminate these drawbacks, maintain a constant average channel temperature of the FET even with variations in the input pulse repetition rate and pulse width, and achieve reliability with low power consumption. The object of the present invention is to provide a power amplifier that does not have 7-7''-

(Configuration of the Invention) The configuration of the power amplifier of the present invention includes a divider that divides a high-frequency input signal into two, an amplifier circuit to which one of the two divided signals is input, a detector to which the other is input, and a detector that detects the signal. a detection circuit that detects the pulse repetition rate and pulse width of the high-frequency input signal from the input signal, and a detection circuit that detects the pulse repetition rate and pulse width of the high-frequency input signal; a signal generating circuit that generates a drain voltage from the detection circuit that always brings the drain voltage of the FET to an optimum state so that the channel temperature is constant; It is configured to include a control circuit that supplies the FBT in use.

(Example) Next, the present invention will be described in detail with reference to the drawings.

, FIG. 2 is a block diagram showing a power amplifier according to an embodiment of the present invention. In the figure, an amplifier circuit 11 may be substantially the same as the conventional power amplifier shown in FIG. Now, the high frequency input signal input from the input terminal 12 is divided into two by the divider 16, one is input to the amplifier circuit 11, the other is input to the detector 17, and the detected signal is sent to the detection circuit 18. Sent.

This detection circuit 18 detects the pulse repetition rate and pulse width from the detected signal, and each detected data is supplied to the next signal generation circuit 19. In the signal generation circuit 19,
The pulse repetition rate and pulse width and the value of the drain voltage shown in FIG. Based on the detected data on the rate and pulse width, the signal generating circuit 19 generates the optimal drain voltage to keep the average channel temperature constant. The optimum drain voltage obtained by this signal generation circuit 19 is determined by the control circuit 20.
, a pulsed optimum drain voltage is applied to the FET of the high-frequency input signal pulse and the pulse width circuit 11.

In the above embodiment, a part of the high-frequency input signal of the power amplifier is emitted and detected to detect the state of the input pulse, but in addition to this, a pulse synchronized with the pulse of the high-frequency input signal is received from the outside. A circuit that detects the repetition rate and pulse width from the lever pulse may be used.

(Effects of the Invention) As explained above, according to the present invention, the pulse repetition rate and pulse width of a high-frequency input signal are detected, and the drain voltage is adjusted based on the detection results so that the average channel temperature of the FET is constant. automatically changes the drain voltage to a pulse corresponding to the pulse of the high frequency signal.
After that, the pulses are supplied to the drains of the respective 0FETs, resulting in low power consumption, the repetition rate of the pulses, and the valve temperature can be maintained at optimum conditions, and the pulses can be amplified without impairing reliability. Since the temperature is lower than in the conventional constant via method, effects such as higher power output can be obtained if the temperature is allowed to rise to the same level as in the conventional method.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional power amplifier, Fig. 2 is a block diagram showing a power amplifier according to an embodiment of the present invention, and Fig. 3 shows input pulse repetition rate, pulse width, and optimum drain of PET. FIG. 3 is a characteristic diagram showing the relationship with voltage. In the figure, 1...FB'l', 2.12...Input terminal, 3.13...Output terminal, 4.14...
Gate voltage terminal, 5.15...Drain voltage terminal, 11...Amplifier circuit, 16...Distributor, 17...Detector, 18... . . . detection circuit, 19 . . . signal generation circuit, 20 . . . control circuit. ￥-2-Toppling 3@

Claims (1)

[Claims] a divider that divides a high-frequency input signal into two; an amplifier circuit having a high-frequency power amplification element that amplifies one signal from the divider; a detector that detects the other signal from the divider; a detection circuit that detects the pulse repetition rate and pulse width of the high-frequency input signal from the signal detected by the high-frequency input signal; A signal generation circuit that generates an optimal bias voltage to be applied to a power amplification element, and a control circuit that supplies the bias voltage to the high frequency power amplification element in response to pulses of the high frequency input signal. A power amplifier featuring: