JPS6333910A - Fet amplifier - Google Patents

Abstract

PURPOSE: To suppress the passing phase change in the entire FET amplifier by giving a phase signal extracted from two couplers to a control circuit controlling the phase of a 2nd amplifier through a phase detector detecting the phase difference of the coupler side and applying it further to a 2nd amplifier. CONSTITUTION:A coupler 6 is used to extract a little of microwave signal at an input signal terminal 2 and at an output signal terminal 3, the extracted signal is inputted to a phase detector 7 to detect the phase difference among input/output terminals 2-3. Since the phase detection signal does not drive a 2nd amplifier 4 as it is, the, signal is converted into a proper control signal in the control circuit 8 and then fed to the 2nd amplifier 4. That is, the phase change generated in a unit amplifier 1 is extracted by a phase detector 4 and the polarity of the phase change is inverted by the 2nd amplifier 4 through the control of the control circuit 6. Thus, the phase change as the entire FET amplifier is made zero.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an F having a phase compensation function for microwave signals.
ET (is about a valve effect transistor 2 amplifier).

[Conventional technology]

FIG. 3 shows an example of a conventional IF11iT amplifier, and +1) IIi? 1! : A unit amplifier using T is connected to (2) and (3) at the input signal terminal and output signal terminal.

Conventional 11! lFETFET amplifier created for the purpose of amplifying WK high-level microwave signals in tT.
? 1! : Because it has many advantages compared to traveling wave tube amplifiers, etc., which are in opposition to T amplifiers.

Its usage is increasing.

Advantages include low distortion due to low phase change and low saturation characteristics, improved reliability due to the use of solid-state elements, small size and light weight, and the above advantages can be fully utilized in the field of application. Satellite communication lines using microwave technology are playing a major role.

[Problem that the invention seeks to solve]

The conventional FET amplifier as described above has a secondary problem. That is, the power consumption of the amplifier that handles high-level microwave signals as described above is determined according to the power level of the output signal.

Here, it is desirable to operate the FFXTFET amplifier at high power consumption, that is, high efficiency, but on the other hand, the increase in efficiency is at odds with the linearity of the amplifier. This reduction in linearity contrary to efficiency has caused a problem in that the low distortion of the FET amplifier is impaired and the 0 phase characteristics are also deteriorated.

FIG. 4 is an example of the phase characteristics and amplitude characteristics of the above-mentioned FET amplifier with respect to the relative input power level. The amplitude characteristics show that the relative output power saturates as the relative input power increases, and if we pay particular attention to the phase characteristics, the amount of change in one phase increases significantly as the linearity of the FET amplifier deteriorates. You can see that

This invention was made in order to solve such problems, and it is possible to prevent the deterioration of the phase characteristics due to the saturation of the FET amplifier as described above, suppress phase changes, and provide a highly efficient PK.
'! ``The purpose is to obtain an amplifier.

[Means for solving problems]

In the FET amplifier according to the present invention, the FET used in the first amplifier is connected to the conventional first amplifier input @ using FIT.
A second amplifier using a dual-gate FET (different from !) is connected in series, and the input terminal of the second amplifier and the second ! A coupler is connected to the output terminals of the amplifiers, and the phase signals extracted from the two couplers are passed through a phase detector to detect the phase difference on the coupler side, and the phase of the second amplifier is controlled. After connecting to the circuit, it is applied to the second amplifier.

[Effect]

In this invention, the second amplifier connected in series to the conventional first amplifier performs phase adjustment in accordance with the phase change when the PET amplifier is saturated.

〔Example〕

W. Figure 1 is a configuration diagram showing an embodiment of the present invention. In Figure 1, (1) to (3) are all the same as the conventional device. (4) is the conventional first amplifier. connected in series with.

and a second amplifier using a dual-gate IFET different from the FIT used in the first amplifier.

(5) are two couplers connected to the output terminal of the first amplifier and the input terminal of the second amplifier, (6) is the reflective terminal terminator of the coupler, (71Fi) the two couplers (5) A phase detector (8) mixes the signals extracted from the phase detector and extracts the phase difference component, and converts the signal from the phase detector (7) into a control signal and applies it to the dual gate FF1T amplifier 14). This is a control circuit for

Figure 2 shows an example of the internal configuration of the second amplifier +4) shown in the above embodiment, which is equivalent to the conventional device. C1G is a choke coil that prevents the microwave signal from easily leaking out of the bias, (Iυ is a dual gate PIT, (Ir!J is a dual gate) PET flll drain bias terminal.

(1311d first gate bias terminal, 0 is the control circuit (
5) Dual game) FET Cl1
This is a control terminal for applying voltage to the second gate of l.

In the F'ET amplifier configured as described above.

@1 The unit amplifier (1) shown in the diagram is the input signal terminal (2)
As the microwave signal power of
It saturates from the beginning toward the input stage. On this occasion.

As explained in the conventional circuit, the phase of the signal passing through the unit amplifier (1) changes as the amplitude saturates.

The coupler (61) is for extracting a small amount of the microwave signal at the input signal terminal (2) and output signal terminal (3), and the extracted signal is input to the phase detector ()) and is input to the input/output terminal ( The phase difference between 2) and (3) is used laterally. Since the phase detection signal cannot directly drive the second amplifier 14), it is converted into an appropriate control signal in the control circuit (8) and then applied to the second amplifier (4).

In other words, the phase change generated in the unit amplifier +1) is extracted by the phase detector (4), and the polarity of the phase change is reversed and detected by the second amplifier (4). If controlled by the control circuit (61), it is possible to make the amount of phase change of the entire FET amplifier zero. Here, FIG. This is the inside of the second amplifier (4).The amplifier (4) changes the gate-source junction capacitance of the dual gate FKTQII according to the voltage applied to the control terminal α4, thereby allowing the microwave to pass through the dual gate FITα11. It is possible to adjust the phase of the signal, and when combined with the amplification function of the dual gate KTα, it constitutes a good phase shift amplifier.

〔Effect of the invention〕

As explained above, the present invention detects the phase of the microwave signal passing through the conventional first amplifier using two couplers and a phase detector, and uses this detection signal to detect the phase of the microwave signal passing through the conventional first amplifier.
The configuration of driving the second amplifier using a dual-gate FET (different from that used in the FET amplifier) has the effect of suppressing the change in the passing phase of the entire FET amplifier.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing one embodiment of the present invention, and Fig. 2 is a dual gate FE'! shown in Fig. 1. FIG. 3 and FIG. 4 are block diagrams showing a conventional FET amplifier and an example of a custom-made phase and amplitude thereof. In the figure, (1) is a level amplifier, +21f3Lld
The input signal and output signal terminals, 14) are connected to the second amplifier, (
5) is coupler, (6) is v! : Terminal, (7) is a phase detector, (8) is a control circuit. (9) is a block capacitor, and the other is a choke coil. αB is a dual gate) FET, α2 is a drain bias terminal, α9 is a first gate bias terminal, (14 is a control terminal. In addition, the same reference numerals in each figure indicate the same or corresponding parts. Masuo Oiwa, a craftsman No. 1 Figure 1: Unit 1 Width 7: Sougeki Tabi Omote Kago No. 2 Ef!J 11: Te) - Furukate FE Ding 14: Control @ 燗子 @ 3 Blade No. 4 Figure 20-15-do -50 Relative degree input power (dB)

Claims (1)

[Claims] A multistage first amplifier configured using FETs (field effect transistors), and a dual gate FET connected in series to the input side of the first amplifier and different from the FET used in the first amplifier. a second amplifier used;
two couplers connected to each of the input terminal of the second amplifier and the output terminal of the first amplifier; and a phase detector connected to the two couplers for detecting a phase difference between the couplers. and a control circuit connected to the phase detector and the second amplifier and for controlling the phase of the second amplifier.