# US 5,708,292 A · Power amplification circuit

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- Number: US 5,708,292 A
- Document ID: US5708292A
- Status: Granted
- Kind: A
- Application number: 08/704,163
- Filed: 1996-08-28
- Granted: 1998-01-13
- Earliest claimed: 1995-08-29
- Assignees: Matsushita Electronics Corporation
- Inventors: Hidetoshi Furukawa; Daisuke Ueda
- Web page: https://patentgrep.com/patent/US5708292A

## CPC

- H03F 3/1935: {with junction-FET devices}
- H03F 1/306: {in junction-FET amplifiers (H03F1/303, H03F1/305, H03F1/309 take precedence)}
- H10D 62/405: {Orientations of crystalline planes}
- H10D 64/411: {for FETs}
- H03F: AMPLIFIERS
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

Variations in the waveform of high-frequency signals amplified by a field-effect transistor (FET) in a power amplification circuit due to changes in temperature are reduced. A FET having an n-type active layer, a source electrode, a drain electrode and a gate electrode is formed on a (1 0 0)-crystal plane of a semi-insulating GaAs substrate. The FET is protected by a passivation film. The angle .theta., formed between the longitudinal axial direction of the gate electrode and the <0 -1 -1>-direction, is set at an angle of from 0.degree. to 90.degree. corresponding to the impurity concentration of the n-type active layer, in order that the temperature coefficient of the FET threshold voltage becomes substantially equal to the temperature coefficient of the gate bias voltage applied from a power supply to the gate electrode. If the angle .theta. is set at 45.degree., then the temperature coefficient of the FET threshold voltage becomes zero.

## Claims

### Claim 1

A power amplification circuit comprising a field-effect transistor for amplifying the power of an in, high-frequency signal and a voltage generation circuit for generating a gate bias voltage to said field-effect transistor,
said field-effect transistor comprising:
an active layer formed on a (1 0 0)-crystal plane of a compound semiconductor substrate;
a source electrode and a drain electrode, each of said source and drain electrodes forming an ohmic junction with said active layer; and
a gate electrode which forms a Schottky junction with said active layer;
wherein:
an angle .theta., formed between the longitudinal axial direction of said gate electrode and the <0 -1 -1>-direction of said compound semiconductor substrate, is set so as to fall in the range from 0.degree. to 90.degree. in order that a temperature coefficient of the threshold voltage of said field-effect transistor becomes substantially equal to a temperature coefficient of said gate bias voltage.

### Claim 2 (depends on 1)

A power amplification circuit according to claim 1 wherein said angle .theta. is set according to the impurity concentration of said active layer.

### Claim 3 (depends on 1)

A power amplification circuit according to claim 1 wherein said angle .theta. is 45.degree..

### Claim 4

A power amplification circuit comprising a field-effect transistor for amplifying the power of an input high-frequency signal and an input matching circuit connected between a signal source and said field-effect transistor,
said field-effect transistor comprising:
an active layer formed on a (1 0 0)-crystal plane of a compound semiconductor substrate;
a source electrode and a drain electrode, each of said source and drain electrodes forming an ohmic junction with said active layer; and
a gate electrode which forms a Schottky junction with said active layer and is connected to said input matching circuit;
wherein:
an angle .theta., formed between the longitudinal axial direction of said gate electrode and the <0 -1 -1>-direction of said compound semiconductor substrate, is set so as to fall in the range from 0.degree. to 90.degree. in order that a temperature coefficient of the input impedance real part of said field-effect transistor becomes substantially equal to a temperature coefficient of the output impedance real part of said input matching circuit.

### Claim 5 (depends on 4)

A power amplification circuit according to claim 4 wherein said angle .theta. is set according to the impurity concentration of said active layer.

### Claim 6 (depends on 4)

A power amplification circuit according to claim 4 wherein said angle .theta. is 45.degree..