THERMAL SENSORS AND METHODS OF OPERATING THEREOF

• US 20110255568A1
• Filed: 06/30/2011
• Published: 10/20/2011
• Est. Priority Date: 04/22/2009
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: SWEI, Steven
• Granted Patent: US 9,004,754 B2
• Time in Patent Office: Days
• US Class Current: 374/180
• CPC Class Codes: G01K 2219/00 Thermometers with dedicated analog to digital converters
• CPC Class Codes: G01K 7/01 using semiconducting elements having PN junctions G01K7/02, G01K7/16, G01K7/30 take precedence

Abstract

A thermal sensor includes a comparator having a first and second input nodes. A reference voltage generator is electrically coupled with the first input node. The reference voltage generator is configured to provide a reference voltage that is substantially temperature-independent. A temperature sensing circuit is electrically coupled with the second input node. The temperature sensing circuit is configured to provide a temperature-dependent voltage. The temperature sensing circuit includes a current mirror. A first metal-oxide-semiconductor (MOS) transistor is electrically coupled between the current mirror and ground. A first resistor is electrically coupled with the current mirror. A second MOS transistor is electrically coupled with the first resistor in series. The second MOS transistor and the first resistor are electrically coupled with the first MOS transistor in a parallel fashion.

Claims

1. A thermal sensor comprising:

a comparator having a first and second input nodes;

a reference voltage generator electrically coupled with the first input node of the comparator, the reference voltage generator being configured to provide a reference voltage that is substantially temperature-independent; and

a temperature sensing circuit electrically coupled with the second input node of the comparator, the temperature sensing circuit being configured to provide a temperature-dependent voltage, wherein the temperature sensing circuit comprises;

a current mirror;

a first metal-oxide-semiconductor (MOS) transistor electrically coupled between the current mirror and ground, wherein a first node is between the first MOS transistor and the current mirror;

a first resistor electrically coupled with the current mirror, wherein a second node is between the first resistor and the current mirror; and

a second MOS transistor electrically coupled with the first resistor in series, wherein the second MOS transistor and the first resistor are electrically coupled with the first MOS transistor in a parallel fashion.

2. The thermal sensor of claim 1, wherein the first and second MOS transistors are operable in a sub-threshold region during a sensing operation of the thermal sensor.

3. The thermal sensor of claim 1, wherein the temperature sensing circuit is a complementary-to-absolute-temperature (CTAT) sensing circuit.

4. The thermal sensor of claim 3, wherein the first node is electrically coupled with the second input node of the comparator.

5. The thermal sensor of claim 4, further comprising:

a third MOS transistor electrically coupled with a power source voltage;

a fourth MOS transistor electrically coupled with the third MOS transistor in series;

a second resistor electrically coupled between the first node and a third node between the third and fourth transistors; and

a third resistor electrically coupled between the third node and the second node.

6. The thermal sensor of claim 5, wherein the fourth MOS transistor is operable in a sub-threshold region during a sensing operation of the thermal sensor.

7. The thermal sensor of claim 1, wherein the temperature sensing circuit is a proportional-to-absolute-temperature (PTAT) sensing circuit.

8. The thermal sensor of claim 7, further comprising:

a third MOS transistor electrically coupled with a power source voltage, wherein a gate of the third MOS transistor is electrically coupled with the current mirror; and

a second resistor electrically coupled with the third MOS transistor in series, wherein a third node between the third MOS transistor and the second resistor is electrically coupled with the first input node of the comparator.

9. The thermal sensor of claim 8, further comprising:

a fourth MOS transistor electrically coupled with a power source voltage;

a fifth MOS transistor electrically coupled with the third MOS transistor in series, wherein a fourth node is between the fourth and fifty MOS transistors;

a third resistor electrically coupled between the fourth node and the first node; and

a fourth resistor electrically coupled between the fourth node and the second node.

10. The thermal sensor of claim 9, wherein the fifth MOS transistor is operable in a sub-threshold region during a sensing operation of the thermal sensor.

11. A thermal sensor comprising:

a comparator haying a first and second input nodes;

a reference voltage generator electrically coupled with the first input node of the comparator, the reference voltage generator being configured to provide a reference voltage that is substantially temperature-independent; and

a complementary-to-absolute-temperature (CTAT) sensing circuit electrically coupled with the second input node of the comparator, the CTAT sensing circuit being configured to provide a temperature-dependent voltage, wherein the CTAT sensing circuit comprises;

a current mirror;

a first metal-oxide-semiconductor (MOS) transistor electrically coupled between the current mirror and ground, wherein a first node is between the first MOS transistor and the current mirror;

a first resistor electrically coupled with the current mirror, wherein a second node is between the first resistor and the current mirror; and

a second MOS transistor electrically coupled with the first resistor in series, wherein the second MOS transistor and the first resistor are electrically coupled with the first MOS transistor in a parallel fashion, and the first and second MOS transistors are operable in a sub-threshold region during a sensing operation of the thermal sensor.

12. The thermal sensor of claim 11, wherein the first node is electrically coupled with the second input node of the comparator.

13. The thermal sensor of claim 12, further comprising:

a third MOS transistor electrically coupled with a power source voltage;

a fourth MOS transistor electrically coupled with the third MOS transistor in series;

a second resistor electrically coupled between the first node and a third node between the third and fourth transistors; and

a third resistor electrically coupled between the third node and the second node.

14. The thermal sensor of claim 13, wherein the fourth MOS transistor is operable in a sub-threshold region during the sensing operation of the thermal sensor.

15. A thermal sensor comprising:

a comparator having a first and second input nodes;

a reference voltage generator electrically coupled with the first input node of the comparator, the reference voltage generator being configured to provide a reference voltage that is substantially temperature-independent; and

a proportional-to-absolute-temperature (PTAT) sensing circuit electrically coupled with the second input node of the comparator, the PTAT sensing circuit being configured to provide a temperature-dependent voltage, wherein the PTAT sensing circuit comprises;

a current mirror;

a first metal-oxide-semiconductor (MOS) transistor electrically coupled between the current mirror and ground, wherein a first node is between the first MOS transistor and the current mirror;

a first resistor electrically coupled with the current mirror, wherein a second node is between the first resistor and the current mirror; and

a second MOS transistor electrically coupled with the first resistor in series, wherein the second MOS transistor and the first resistor are electrically coupled with the first MOS transistor in a parallel fashion, and the first and second MOS transistors are operable in a sub-threshold region during a sensing operation of the thermal sensor.

16. The thermal sensor of claim 15, further comprising:

a third MOS transistor electrically coupled with a power source voltage, wherein a gate of the third MOS transistor is electrically coupled with the current mirror; and

a second resistor electrically coupled with the third MOS transistor in series, wherein a third node between the third MOS transistor and the second resistor is electrically coupled with the first input node of the comparator.

17. The thermal sensor of claim 16, further comprising:

a fourth MOS transistor electrically coupled with a power source voltage;

a fifth MOS transistor electrically coupled with the third MOS transistor in series, wherein a fourth node is between the fourth and fifty MOS transistors;

a third resistor electrically coupled between the fourth node and the first node; and

a fourth resistor electrically coupled between the fourth node and the second node.

18. The thermal sensor of claim 17, wherein the fifth MOS transistor is operable in a sub-threshold region during a sensing operation of the thermal sensor.