JPH0528111U - Phase compensation high power amplifier - Google Patents

Abstract

(57) [Summary] [Purpose] The AM / PM conversion coefficient can be minimized,
Provided is a high output amplifier that does not deteriorate the transmission quality of a microwave signal. [Structure] A microwave signal is input from an input terminal 6 to a phase shifter 1 and its phase is controlled according to the magnitude of a control voltage b, then amplified by a plurality of unit amplifiers 2 and input to a final stage amplifier 3. It The final stage amplifier 3 includes a gate resistor 5
FE for obtaining a gate bias from the bias power supply 8 via the
The T-transistor amplifies the microwave signal and outputs it to the output terminal 7. F from both ends of the gate resistor 5
The voltage generated by the gate current Ig of the ET transistor is detected, and this is amplified by the DC amplifier 4 with an appropriate amplification degree to be the above-mentioned control voltage b.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a phase compensation high power amplifier used in the microwave band.

[0002]

[Prior Art]

 A conventional high-power amplifier in the microwave band will be described with reference to the block diagram shown in FIG. 3 and the characteristic diagram of the final stage amplifier 3 used in the conventional example of FIG. 3 shown in FIG.

A conventional high-power amplifier that amplifies a microwave signal to a high output amplifies a low-power signal Pin input to an input end 6 by a plurality of unit amplifiers 2 and amplifies a FET transistor provided at the final stage. A high output microwave signal Pout is obtained at the output end 7 by the amplification of the final stage amplifier 3 as an element.

This high-power amplifier amplifies a small signal to a large signal by connecting a large number of unit amplifiers 2 in cascade, but in order to obtain the maximum power supply efficiency, the final stage amplifier 3 saturates the FET transistor. Often used at the output level. FIG. 4 shows the output level (Pout), the phase (phase), and the gate leakage current (Ig) with respect to the input level Pin1 of the final stage amplifier 3. From the point a2 where the output level of the final stage amplifier 3 is almost the saturation level. The phase starts to change rapidly, and the AM / PM conversion coefficient, which is the amount of change in phase with respect to the input level Pin1, suddenly deteriorates. Further, the gate leakage current Ig starts to flow largely in the positive direction from around the point a 2.

[0005]

[Problems to be solved by the device]

 The above-mentioned conventional high-power amplifier has a drawback that it is difficult to operate efficiently because the AM / PM conversion coefficient sharply deteriorates near the output saturation level and the transmission quality of the microwave signal deteriorates. .

[0006]

[Means for Solving the Problems]

 The phase compensating high output amplifier of the present invention uses a phase shifter for shifting a microwave signal by a control voltage and an FET transistor connected to a stage subsequent to the phase shifter to obtain a gate bias by a gate resistor as amplifying elements. It has an amplifier and a control circuit for producing the control voltage from a voltage detected from both ends of the gate resistor.

[0007]

【Example】

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of a phase compensation high output amplifier according to the present invention, and FIG. 2 is a characteristic diagram thereof.

The phase shifter 1 of the phase compensation high output amplifier shifts the phase of the microwave signal Pin input to the input terminal 6 according to the magnitude of the control voltage b. The microwave signal output from the phase shifter 1 is amplified by a plurality of unit amplifiers 2 connected in cascade, and input to the final stage amplifier 3. The final stage amplifier 3 amplifies the input microwave signal by the FET transistor which obtains a gate bias from the bias power source 8 via the gate resistor 5, and outputs the output microwave signal Pout to the output end 7. The gate current Ig of the FET transistor included in the final stage amplifier 3 is flowing in the gate resistor 5, and the voltage detected from both ends of the gate resistor 5 is input to the DC amplifier 4 which is a control circuit. , Is amplified by an appropriate amplification degree to generate the control voltage b. One or both of the phase shifter 1 and the DC amplifier 4 are designed not to operate unless the gate current Ig is positive.

When the input level Pin of the microwave signal to the input end 6 increases and the output level Pout at the output end 7 reaches the saturated output level a1 due to the saturation of the final stage amplifier 3, the gate leakage current Ig also becomes positive. The flow starts to flow rapidly (see Fig. 4 in the explanation of the conventional example). At this time, the voltage across the gate resistor 5 also increases. This both-end voltage is amplified by the DC amplifier 4, and the amount of phase shift of the phase shifter 1 is set as the control voltage b in the direction of canceling the phase change of the final stage amplifier 3. The phase shifter 1 controlled by the control voltage b cancels the phase change generated by the final stage amplifier 3. Therefore, as shown in FIG. 2, the output phase phase with respect to the input level Pin of the complementary high-power amplifier of FIG. 1 does not change much even at the saturated output level a1. In this way, the present embodiment minimizes the increase in the AM / PM conversion coefficient generated by the final stage amplifier 3.

[0011]

[Effect of the device]

 As described above, the present invention detects the voltage across the gate resistor that supplies the gate bias of the FET transistor included in the final stage amplifier, and mainly uses the control voltage created from this to detect the phase change generated by the final stage amplifier. The AM / PM conversion coefficient can be minimized by controlling the amount of phase shift of the phase shifter placed before the final-stage amplifier in the direction of cancellation, and the deterioration of microwave signal transmission quality can be reduced. Instead, the amplifier can be operated with high efficiency.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment according to the present invention.

FIG. 2 is a characteristic diagram of the embodiment of FIG.

FIG. 3 is a block diagram of a conventional example.

FIG. 4 is a characteristic diagram of a final stage amplifier 3 used in the conventional example of FIG.

[Explanation of symbols]

 1 Phase shifter 2 Unit amplifier 3 Final stage amplifier 4 DC amplifier 5 Gate resistor 6 Input terminal 7 Output terminal 8 Bias power supply

Claims (1)

[Scope of utility model registration request] 1. A phase shifter for shifting a microwave signal according to a control voltage, an amplifier connected to a stage subsequent to the phase shifter and using an FET transistor for obtaining a gate bias by a gate resistor as an amplifying element, and the gate resistor. And a control circuit for generating the control voltage from a voltage detected from both ends of the container.