# US 9,435,696 B2 · Temperature sensor circuit and semiconductor device including temperature sensor circuit

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- Number: US 9,435,696 B2
- Document ID: US9435696B2
- Status: Granted
- Kind: B2
- Application number: 13/873,550
- Filed: 2013-04-30
- Published: 2013-11-07
- Granted: 2016-09-06
- Earliest claimed: 2012-05-02
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Applicants: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Jun Koyama; Shunpei Yamazaki
- Web page: https://patentgrep.com/patent/US9435696B2

## CPC

- G01K 7/01: using semiconducting elements having PN junctions (G01K7/02, G01K7/16, G01K7/30 take precedence)
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)

## Abstract

To provide a highly accurate temperature sensor circuit. The temperature sensor circuit includes a first constant current circuit; a first diode in which a first voltage reflecting the temperature of an object to be detected is generated between an anode and a cathode in accordance with a first current supplied from the first constant current circuit; a second constant current circuit; a second diode which includes an oxide semiconductor and in which a second voltage is generated between an anode and a cathode in accordance with a second current supplied from the second constant current circuit; and an amplifier circuit which amplifies a difference between the first voltage and the second voltage.

## Claims

### Claim 1

A temperature sensor circuit comprising:
a first constant current circuit;
a first semiconductor element where a first voltage is generated between a pair of terminals in accordance with a first current supplied from the first constant current circuit;
a second constant current circuit;
a second semiconductor element where a second voltage is generated between a pair of terminals in accordance with a second current supplied from the second constant current circuit; and
an amplifier circuit which amplifies a difference between the first voltage and the second voltage,
wherein a rate of change in the first voltage with a first temperature of the first semiconductor element is greater than a rate of change in the second voltage with a second temperature of the second semiconductor element,
wherein a value of the first temperature is the same as a value of the second temperature,
wherein the second semiconductor element comprises an oxide semiconductor, and
wherein the first semiconductor element comprises a semiconductor other than the oxide semiconductor.

### Claim 2 (depends on 1)

The temperature sensor circuit according to claim 1
wherein the oxide semiconductor comprises In, Ga, and Zn.

### Claim 3 (depends on 1)

The temperature sensor circuit according to claim 1,
wherein at least one of the first semiconductor element and the second semiconductor element is a diode.

### Claim 4 (depends on 1)

The temperature sensor circuit according to claim 1,
wherein a value of the first current is equal to a value of the second current.

### Claim 5

A semiconductor device comprising:
a temperature sensor circuit which generates a signal;
an output device; and
a signal processing circuit which controls operation of the output device using the signal,
wherein the temperature sensor circuit comprises:
a first constant current circuit;
a first semiconductor element where a first voltage is generated between a pair of terminals in accordance with a first current supplied from the first constant current circuit;
a second constant current circuit;
a second semiconductor element where a second voltage is generated between a pair of terminals in accordance with a second current supplied from the second constant current circuit; and
an amplifier circuit which amplifies a difference between the first voltage and the second voltage and generates the signal, and
wherein a rate of change in the first voltage with a first temperature of the first semiconductor element is greater than a rate of change in the second voltage with a second temperature of the second semiconductor element,
wherein a value of the first temperature is the same as a value of the second temperature,
wherein the second semiconductor element comprises an oxide semiconductor, and
wherein the first semiconductor element comprises a semiconductor other than the oxide semiconductor.

### Claim 6 (depends on 5)

The semiconductor device according to claim 5,
wherein the output device is a liquid crystal display device.

### Claim 7 (depends on 6)

The semiconductor device according to claim 6,
wherein each pixel of the liquid crystal display device includes a liquid crystal element, and
wherein the temperature depends on a temperature of a liquid crystal layer included in the liquid crystal element.

### Claim 8 (depends on 7)

The semiconductor device according to claim 7,
wherein the signal processing circuit is configured to adjust a voltage applied to the liquid crystal element using the signal to control operation of the output device.

### Claim 9 (depends on 5)

The semiconductor device according to claim 5,
wherein the oxide semiconductor comprises In, Ga, and Zn.

### Claim 10 (depends on 5)

The semiconductor device according to claim 5,
wherein at least one of the first semiconductor element and the second semiconductor element is a diode.