# US 5,347,142 A · Modes of infrared hot electron transistor operation in infrared detection

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- Number: US 5,347,142 A
- Document ID: US5347142A
- Status: Granted
- Kind: A
- Application number: 08/082,316
- Filed: 1993-06-25
- Granted: 1994-09-13
- Earliest claimed: 1993-06-25
- Assignees: The United States of America as represented by the Secretary of the Army
- Inventors: Kwong-Kit Choi
- Web page: https://patentgrep.com/patent/US5347142A

## CPC

- H10F 30/245: {Bipolar phototransistors}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

A circuit incorporating an infrared hot electron transistor having a common base and biasing voltages. In one embodiment, the circuit is configured to take advantage of the photovoltage amplification capabilities of the infrared hot electron transistor. In another embodiment, the infrared hot electron transistor is configured to take advantage of the photovoltaic mode of operation of the infrared hot electron transistor. The present invention can therefore be used to directly replace a photodiode used in infrared detection. The present invention additionally provides an amplified output voltage and permits direct DC coupling to a high gain operational amplifier.

## Claims

### Claim 1

An infrared detection circuit comprising:
an infrared hot electron transistor having an emitter, base, and collector, the base being common;
an emitter voltage supply connected between the emitter and the base;
a collector voltage supply connected between the collector and the base; and
a load connected between the collector and said collector supply voltage,
wherein an amplified output voltage is obtained when infrared radiation is detected by said infrared hot electron transistor and wherein: ##EQU8## wherein, R.sub.L =the value of said load,
r=the value of the internal resistance between the emitter and the base, and
.alpha.=the value of said infrared hot electron transistor photocurrent transfer ratio.

### Claim 2

An infrared detection circuit comprising:
an infrared hot electron transistor having an emitter, base, and collector, the base being common;
an emitter voltage supply connector between the emitter and the base;
a collector voltage supply connected between the collector and the base;
a load connected between the collector and said collector voltage supply; and
a non-inverting constant gain multiplier coupled between the collector and the base of said infrared hot electron transistor, wherein the photovoltage is amplified.

### Claim 3 (depends on 2)

An infrared detection circuit as in claim 2 wherein:
said non-inverting constant gain multiplier is DC coupled.

### Claim 4 (depends on 2)

An infrared detection circuit as in claim 2 wherein:
said non-inverting constant gain multiplier includes an operational amplifier.