Integrated electronic device comprising a temperature sensor and sensing method

Patent metadata

Field	Value
Publication number	US-10317293-B2
Application number	US-201514958786-A
Country	US
Kind code	B2
Filing date	Dec 3, 2015
Priority date	Mar 30, 2015
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

A sensing element integrated in a semiconductor material chip has a sensing diode of a junction type configured to be reverse biased so that its junction capacitance is sensitive to the local temperature. A reading stage is coupled to the sensing element for detecting variations of the junction capacitance of the sensing diode and outputting a reading acquisition signal proportional to the local temperature of the sensing diode. The sensing diode has a cathode terminal coupled to a biasing node and an anode terminal coupled to a first input of the reading stage. The biasing node receives a voltage positive with respect to the first input of the reading stage for keeping the sensing diode reverse biased.

First claim

The invention claimed is:

1. A temperature sensor device comprising a sensing element integrated in a semiconductor material chip and sensitive to temperature, the sensing element including a sensing diode of a junction type configured to be reverse biased and the temperature sensor device including a sensing stage coupled to the sensing element, the sensing diode having a cathode terminal coupled to a biasing node and an anode terminal coupled to a first input of the sensing stage, wherein the biasing node is configured to receive a voltage that is positive with respect to a voltage on the first input of the sensing stage and which switches between a low value and a high value causing a reverse voltage step to be applied across the sensing diode, wherein the sensing stage is configured to detect a capacitance variation of the sensing diode as a function of temperature in response to the reverse voltage step applied across the sensing diode and is configured to output a voltage that is a function of the capacitance variation of the sensing diode.

2. The temperature sensor device according to claim 1 , further comprising a reference capacitive element having a first terminal coupled to the biasing node and a second terminal coupled to a second input of the sensing stage.

3. The temperature sensor device according to claim 2 , wherein the sensing diode has junction capacitance at room temperature and the reference capacitive element has a reference capacitance of the same value as the junction capacitance at room temperature.

4. The temperature sensor device according to claim 2 , further comprising a compensation diode having its anode terminal coupled to the second input of the sensing stage and its cathode terminal coupled to a reference potential line, and a symmetry capacitor having a first terminal coupled to the first input of the sensing stage and a second terminal coupled to the reference potential line.

5. The temperature sensor device according to claim 4 , wherein the sensing stage is a switched capacitor differential amplifier.

6. A sensing system, comprising:
a sensing element including a sensing junction diode;
a reading circuit coupled to the sensing element, the reading circuit configured to reverse bias the sensing junction diode and detect a junction capacitance of the sensing junction diode, and configured to generate an output signal based on the detected junction capacitance, the output signal indicating a temperature of an environment containing the junction diode; and
a compensation circuit coupled to the sensing junction diode and configured to compensate for a leakage current through the sensing junction diode.

7. The sensing system of claim 6 , wherein the compensation circuit comprises a compensation diode formed to have a leakage that is approximately equal to the leakage current of the sensing junction diode.

8. The sensing system of claim 6 , wherein the sensing junction diode has a cathode coupled to a biasing node and an anode coupled to a first input of the reading circuit, wherein the biasing node is coupled to a voltage source configured to supply the biasing node with a voltage that is positive with respect to the first input of the reading circuit.

9. The sensing system of claim 6 , wherein the reading circuit comprises a switched capacitor differential amplifier that generates the output signal having a value given by:

V
o

⁡

(
t
)

∝

Δ
⁢

⁢
C

C
i

⁢
Δ
⁢

⁢
V

where ΔV is a change in value of a biasing voltage applied to the sensing junction diode, ΔC is a difference between the value of the junction capacitance of the sensing junction diode and a value of a reference capacitor of the switched capacitor differential amplifier, and the capacitance C i are values of feedback capacitors of the switched capacitor differential amplifier.

10. The sensing system of claim 9 , wherein the switched capacitor differential amplifier comprises a fully differential amplifier.

11. A temperature sensor device, comprising:
a sensing diode configured to be reverse biased, the reverse biased sensing diode having a junction capacitance that is a function of temperature;
a reference capacitive element having a capacitance that is substantially independent of temperature; and
a sensing stage coupled to the sensing diode and the reference capacitive element, the sensing stage configured to generate an output signal based on a comparison of the junction capacitance of the sensing diode to the capacitance of the reference capacitive element, the output signal indicating a temperature of the sensing diode.

12. The temperature sensor device of claim 11 , wherein the sensing stage includes first and second inputs, and wherein the reference capacitive element includes a first node coupled to a biasing node configured to receive a biasing voltage and a second node coupled to the second input of the reading stage, and wherein the sensing diode has a cathode coupled to the biasing node and an anode coupled to a first input of the reading stage, the biasing voltage being positive with respect to a voltage on the first input of the reading stage.

13. The temperature sensor device according to claim 12 , further comprising:
a compensation diode having an anode coupled to the second input of the reading stage and a cathode coupled to a reference potential node configured to receive a reference voltage; and
a symmetry capacitor having a first node coupled to the first input of the reading stage and a second node coupled to the reference potential node.

14. The temperature sensor device of claim 11 , wherein the sensing stage is configured to detect a change in a current flowing through the sensing diode responsive to a change in a reverse biasing voltage across the sensing diode, the detected change in current indicating a change in capacitance of the sensing diode.

15. The temperature sensor device of claim 14 , wherein the sensing stage is further configured to detect a current through the reference capacitive element responsive to the change in the reverse biasing voltage.

16. The temperature sensor device of claim 15 , wherein the reference capacitive element has a capacitance value that is approximately equal to a value of the junction capacitance of the sensing diode at a room temperature.

17. The temperature sensor device of claim 11 , wherein the sensing stage comprises a switched capacitor operational amplifier.

18. The temperature sensor device of claim 17 , wherein the switched capacitor operational amplifier includes an inverting input, a non-inverting input, and first and second differential outputs, and further comprises a first feedback capacitor coupled between the non-inverting input and the first differential output and a second feedback

Assignees

• St Microelectronics Srl

Inventors

• Vaiana Michele
• Casella Daniele
• Bruno Giuseppe

Classifications

• G01K7/01 Primary

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

• G01K7/34

  using capacitative elements (capacitors per se H01G) · CPC title

• G01K7/343 Primary

  the dielectric constant of which is temperature dependant · CPC title