Temperature sensor

Patent metadata

Field	Value
Publication number	US-11274976-B2
Application number	US-201916709969-A
Country	US
Kind code	B2
Filing date	Dec 11, 2019
Priority date	Dec 11, 2018
Publication date	Mar 15, 2022
Grant date	Mar 15, 2022

Abstract

A temperature sensor supplying a measurement signal varying linearly to within 10% as a function of the temperature at least over a temperature range, including an oscillator supplied by a supply voltage and supplying a first oscillating signal, said oscillator including first MOS transistors, the voltage at each internal node of the oscillator having a dynamic range equal to the supply voltage, the measuring signal corresponding to the supply voltage.

First claim

The invention claimed is:

1. A temperature sensor supplying a measurement signal of the temperature, comprising a controllable current source, an oscillator and a circuit controlling the controllable current source configured to control the equivalent resistance of the oscillator to be equal to a reference resistance, the oscillator being supplied by the controllable current source at a first node having a supply voltage, the oscillator supplying a first oscillating voltage having a dynamic range equal to the supply voltage, the measuring signal corresponding to the supply voltage.

2. The temperature sensor according to claim 1 , wherein the controllable current source comprises a first MOS transistor whose source is configured to be coupled to a source of a high reference potential, whose drain supplies the supply voltage to the first node, and whose gate is controlled by the control circuit.

3. The temperature sensor according to claim 1 , comprising an analog-digital converter receiving the supply voltage and supplying a converted digital signal to the control circuit, the control circuit being configured to select a resistance among several resistances from the converted digital signal, said resistances being substantially equal to the reference resistance in different temperature subranges of a temperature range.

4. The temperature sensor according to claim 3 , comprising a follower circuit receiving the supply voltage and outputting a copy of the supply voltage and wherein the analog-digital converter is coupled to the output of the follower circuit.

5. The temperature sensor according to claim 2 , wherein the control circuit and the controllable current source comprise a current mirror comprising the first MOS transistor and a second MOS transistor, the control circuit further comprising an operational amplifier whose output is coupled to the gates of the first and second MOS transistors, and wherein the first node is coupled to a first input of the operational amplifier and wherein the control circuit comprises a circuit supplying a reference voltage to a second input of the operational amplifier, a current passing through the second MOS transistor, the supply circuit being configured to supply the reference voltage equal to the product of said current and the reference resistance.

6. The temperature sensor according to claim 5 , wherein the circuit supplying the reference voltage is configured to couple the second input to one of said resistances from a selection signal.

7. The temperature sensor according to claim 6 , wherein the control circuit comprises a digital circuit receiving the converted digital signal and determining the selection signal from the converted digital signal in order to select the resistance, among the resistances, substantially equal to the reference resistance.

8. The temperature sensor according to claim 6 , wherein the circuit supplying the reference voltage comprises first resistors, the first resistors having resistances substantially equal to the reference resistance in different temperature subranges of a temperature range, and a demultiplexer configured to couple one of the first resistors to the second input from the selection signal.

9. The temperature sensor according to claim 6 , wherein the circuit supplying the reference voltage comprises a second resistor having a resistance with a positive temperature coefficient coupled to a third resistor having a resistance with a negative temperature coefficient and a circuit configured to modify the ratio between the current circulating in the second resistor and the current circulating in the third resistor.

10. The temperature sensor according to claim 2 , wherein the oscillator comprises third MOS transistors.

11. The temperature sensor according to claim 1 , wherein the first oscillating signal oscillates at a first oscillation frequency, the temperature sensor comprising a frequency divider circuit receiving the first oscillating signal or a second signal oscillating at the first oscillation frequency and supplying a third signal oscillating at a second oscillation frequency that is a sub-multiple of the first oscillation frequency.

12. The temperature sensor according to claim 11 , wherein the analog-digital converter is paced by the third oscillating signal.

13. The temperature sensor according to claim 1 , wherein the oscillator is a ring oscillator.

14. The temperature sensor according to claim 13 , wherein the voltage at each internal node of the oscillator has a dynamic equal to the supply voltage of the oscillator.

15. The temperature sensor according to claim 10 , wherein the third MOS transistors are configured to have a current passing through them varying linearly to within 10% as a function of the temperature over a temperature range, the sensor being configured to supply the measuring signal varying linearly to within 10% as a function of the temperature at least over the temperature range.

16. The temperature sensor according to claim 14 , wherein the temperature range varies from −40° C. to 250° C.

Assignees

• Commissariat Energie Atomique

Inventors

• Badets Franck
• Cozzi Maxime

Classifications

• G01K7/245 Primary

  in an oscillator circuit · CPC title

• H03B5/04

  Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature · CPC title

• G01K7/32

  using change of resonant frequency of a crystal · CPC title

• H03B5/00

  Generation of oscillations using amplifier with regenerative feedback from output to input (H03B9/00, H03B15/00 take precedence) · CPC title

• G01K7/01 Primary

  using semiconducting elements having PN junctions (G01K7/02, G01K7/16, G01K7/30 take precedence) · CPC title