CN109974878B - Temperature sensing circuit - Google Patents

Abstract

A temperature sensing circuit comprises a sensing chip, a bipolar element and a voltage stabilizing capacitor. The sensing chip comprises a sensing end, a reference voltage end, a low voltage end, a current source and a sensing amplifying circuit. The reference voltage end provides a stabilized reference voltage. The low voltage terminal receives a ground voltage. The current source is coupled to the sensing terminal. The sensing amplifying circuit is coupled to the reference voltage terminal and the sensing terminal to provide a temperature-dependent voltage. The bipolar element is provided with a positive terminal and a negative terminal, wherein the positive terminal is coupled with the reference voltage terminal, and the negative terminal is coupled with the sensing terminal. The voltage stabilizing capacitor is coupled between the reference voltage terminal and the ground voltage.

Description

Temperature sensing circuit

Technical Field

The present invention relates to a sensing circuit, and more particularly, to a temperature sensing circuit.

Background

In a computer system, the temperature of the device is monitored by a temperature sensing circuit to maintain the stability of the system. In the temperature sensing circuit, a current is sent to flow through the temperature sensor to sense the voltage across the temperature sensor, thereby obtaining the ambient temperature of the temperature sensor. Since the voltage across the sensing temperature sensor is relatively small, if the temperature sensing circuit is disturbed (e.g., noise is carried on the current path, excess voltage … resulting from too long a conductive wire, etc.), the sensed voltage is distorted, and the voltage value is converted to a temperature value to obtain an incorrect and inaccurate ambient temperature value.

Disclosure of Invention

The present invention provides a temperature sensing circuit, which can suppress the interference on the circuit to improve the accuracy of temperature sensing without increasing the hardware cost.

The temperature sensing circuit of the invention comprises a sensing chip, at least one bipolar element and a voltage stabilizing capacitor. The sensing chip comprises at least one sensing end, a reference voltage end, a low voltage end, a current source and a sensing amplifying circuit. The reference voltage end provides a stabilized reference voltage. The low voltage terminal receives a ground voltage. The current source is coupled to the at least one sensing terminal. The sensing amplifying circuit is coupled to the reference voltage terminal and the at least one sensing terminal to provide a temperature-dependent voltage. The at least one bipolar element has a positive terminal and a negative terminal, wherein the positive terminal is coupled to the reference voltage terminal, and the negative terminal is coupled to the corresponding sensing terminal. The voltage stabilizing capacitor is coupled between the reference voltage terminal and the ground voltage.

The temperature sensing circuit of the invention comprises a sensing chip, at least one bipolar element and a voltage stabilizing capacitor. The sensing chip comprises at least one sensing end, a reference voltage end, a low voltage end, a current source, a voltage stabilizer and a sensing amplifying circuit. The low voltage terminal receives a ground voltage. The current source is coupled to the at least one sensing terminal. The voltage stabilizer is coupled to the reference voltage terminal to provide a stabilized reference voltage to the reference voltage terminal. The positive sensing end of the sensing amplifying circuit is coupled with the at least one sensing end, the negative sensing end of the sensing amplifying circuit is coupled with the reference voltage end, and the positive sensing output end and the negative sensing output end of the sensing amplifying circuit provide temperature-related voltage. The at least one bipolar element has a positive terminal and a negative terminal, wherein the positive terminal is coupled to the corresponding sensing terminal, and the negative terminal is coupled to the reference voltage terminal. The voltage stabilizing capacitor is coupled between the reference voltage terminal and the ground voltage.

Based on the above, the temperature sensing circuit according to the embodiment of the invention utilizes the reference voltage terminal of the sensing chip as the voltage source of the bipolar element to suppress the circuit interference through the voltage regulator. Therefore, the accuracy of temperature sensing can be improved without configuring additional terminals, thereby reducing hardware cost.

In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

FIG. 1 is a circuit diagram of a temperature sensing circuit according to an embodiment of the invention.

FIG. 2 is a circuit diagram of a temperature sensing circuit according to another embodiment of the present invention.

Reference numerals:

100. 200: temperature sensing circuit

110. 110 a: sensing chip

111. 111 a: sensing amplifying circuit

113: analog-to-digital converter

115: voltage stabilizer

AVSS: low voltage of system

BT 1-BT 4, BT1 a-BT 4 a: bipolar transistor

C1-C4: first to fourth capacitors

Cu1, Cu 2: current source

CX 1: voltage stabilizing capacitor

DTR: temperature data

MX1, MX 2: multiplexer

NIN: negative sensing terminal

NOT: negative sensing output terminal

OP 1: operational amplifier

PIN: positive sensing terminal

POT: positive sensing output terminal

PS 1-PS 4: sensing terminal

PVL: low voltage terminal

PVR: reference voltage terminal

SW 1-SW 8: first to eighth switches

SWX 1-SWX 4, SWY 1-SWY 4: switch with a switch body

Vcm: intermediate voltage

Vout 1: temperature dependent voltage

Voutn: negative output voltage

Voutp: positive output voltage

VREF: reference voltage

Φ 1, Φ 2: control signal

Detailed Description

FIG. 1 is a circuit diagram of a temperature sensing circuit according to an embodiment of the invention. Referring to fig. 1, in the present embodiment, a temperature sensing circuit 100 includes a sensing chip 110, at least one bipolar device (here, 4 bipolar transistors BT 1-BT 4 are taken as an example), and a voltage stabilizing capacitor CX 1. The input/output interface of the sense chip 110 has a plurality of pins, and the pins at least include at least one sense terminal (for example, 4 sense terminals PS 1-PS 4 corresponding to 4 bipolar transistors BT 1-BT 4), a reference voltage terminal PVR and a low voltage terminal PVL.

The bipolar transistors BT 1-BT 4 are coupled in a diode type, wherein the bases and collectors of the bipolar transistors BT 1-BT 4 are commonly coupled to the reference voltage terminal PVR to receive the regulated reference voltage VREF, and the emitters of the bipolar transistors BT 1-BT 4 are respectively coupled to the sensing terminals PS 1-PS 4. Further, an emitter of the bipolar transistor BT1 is coupled to the sensing terminal PS1, and an emitter of the bipolar transistor BT2 is coupled to the sensing terminal PS2, which are shown in fig. 1 and will not be described herein. The voltage stabilizing capacitor CX1 is coupled between the reference voltage terminal PVR and the ground voltage. The low voltage terminal PVL receives a ground voltage to provide a system low voltage AVSS.

The sensing chip 110 is configured with at least a multiplexer MX1, a multiplexer MX2, a current source Cu1, a sensing amplifier circuit 111, an analog-to-digital converter 113, and a voltage regulator 115. The voltage regulator 115 is coupled to the reference voltage terminal PVR to provide a regulated reference voltage VREF, i.e., after the reference voltage VREF provided by the reference voltage terminal PVR is regulated by the voltage regulator 115, the voltage ripple is suppressed or even eliminated.

The multiplexer MX1 is coupled between the sensing terminals PS 1-PS 4 and the negative sensing terminal NIN of the sense amplifier circuit 111 and the current source Cu 1. Further, a plurality of input terminals of the multiplexer MX1 are respectively coupled to the sensing terminals PS1 to PS4, and an output terminal of the multiplexer MX1 is coupled to the negative sensing terminal NIN of the sense amplifying circuit 111, so as to be sequentially coupled to the negative sensing terminal NIN of the sense amplifying circuit 111 to one of the sensing terminals PS1 to PS 4. The multiplexer MX2 is coupled between the sensing terminals PS 1-PS 4 and the current source Cu 1. Furthermore, a plurality of input terminals of the multiplexer MX2 are respectively coupled to the sensing terminals PS1 to PS4, and an output terminal of the multiplexer MX2 is coupled to the current source Cu1, so as to sequentially couple the current source Cu1 to one of the sensing terminals PS1 to PS 4. The current source Cu1 is coupled between the output of the multiplexer MX1 and the system low voltage AVSS.

In the embodiment, the positive sensing terminal PIN of the sensing amplifying circuit 111 is coupled to the reference voltage terminal 115, and the negative sensing terminal NIN of the sensing amplifying circuit 111 is coupled to one of the sensing terminals PS1 to PS4 through the multiplexer MX 1. When the negative sensing terminal NIN of the sense amplifying circuit 111 is coupled to the sensing terminal PS1 through the multiplexer MX1, since the reference voltage VREF is a relatively pure voltage source (i.e., the ripple is very low), the voltage difference between the base (corresponding to the positive terminal of the bipolar device) and the emitter (corresponding to the negative terminal of the bipolar device) of the transistor BT1 is related to the ambient temperature around the transistor BT1 and the constant current provided by the current source Cu 1. Then, the sensing amplifier circuit 111 amplifies the reference voltage VREF and the voltage at the sensing terminal PS1, so that the positive sensing output terminal POT and the negative sensing output terminal NOT of the sensing amplifier circuit 111 provide the positive output voltage Voutp and the negative output voltage Voutn, respectively, and the voltage difference between the positive output voltage Voutp and the negative output voltage Voutn is the temperature-dependent voltage Vout 1.

The adc 113 is coupled to the positive sense output terminal POT and the negative sense output terminal NOT of the sense amplifier circuit 111 to receive the temperature-related voltage Vout1, and performs an analog-to-digital conversion on the temperature-related voltage Vout1 to provide temperature data DTR.

In this embodiment, the multiplexer MX1 has switches SWX 1-SWX 4, wherein the switches SWX 1-SWX 4 can fixedly turn on one of the switches SWX 1-SWX 4 according to the temperature sensing requirement, turn on one of the switches SWX 1-SWX 4 according to a specific sequence, or turn on one of the switches SWX 1-SWX 4 according to a specific sequence (for example, select, but not limited to, SWX1, SWX3, and SWX4 in SWX 1-SWX 4, and then turn on according to the sequence of SWX4 → SWX3 → SWX 1), and if there is no temperature sensing requirement, all of the switches SWX 1-SWX 4 can be turned off, which can be determined according to the circuit operation of an external circuit (e.g., a controller, a chipset). In the embodiment, the multiplexer MX2 has switches SWY1 to SWY4, wherein the switches SWY1 to SWY4 are operated synchronously with the switches SWX1 to SWX4, that is, the switches SWY1 and SWX1 are turned on and off simultaneously, the switches SWY2 and SWX2 are turned on and off simultaneously, and the rest is done in the same way.

On the other hand, the sense amplifying circuit 111 includes first to fourth capacitors C1 to C4, first to eighth switches SW1 to SW8, and an operational amplifier OP 1. The first switch SW1 is coupled between the first terminal of the first capacitor C1 and the reference voltage terminal VREF. The second switch SW2 is coupled between the first terminal of the first capacitor C1 and the intermediate voltage Vcm. The third switch SW3 is coupled between the first end of the second capacitor C2 and the output end of the multiplexer MX 1. The fourth switch SW4 is coupled between the first terminal of the second capacitor C2 and the intermediate voltage Vcm.

The fifth switch SW5 is coupled between the second terminal of the first capacitor C1 and the intermediate voltage Vcm. The sixth switch SW6 is coupled between the second terminal of the first capacitor C1 and the positive input terminal of the operational amplifier OP 1. The seventh switch SW7 is coupled between the second terminal of the second capacitor C2 and the intermediate voltage Vcm. The eighth switch SW8 is coupled between the second terminal of the second capacitor C2 and the negative input terminal of the operational amplifier OP 1. The third capacitor C3 is coupled between the positive input terminal of the operational amplifier OP1 and the positive output terminal of the operational amplifier OP 1. The fourth capacitor C4 is coupled between the negative input terminal of the operational amplifier OP1 and the negative output terminal of the operational amplifier OP 1. The positive output terminal of the operational amplifier OP1 is coupled to the positive sensing output terminal POT of the sensing amplifier circuit 111 for outputting the positive output voltage Voutp, and the negative output terminal of the operational amplifier OP1 is coupled to the negative sensing output terminal NOT of the sensing amplifier circuit 111 for outputting the negative output voltage Voutn.

In the present embodiment, the ratio of the first capacitor C1 to the third capacitor C3 determines the gain of the positive output voltage Voutp, and the ratio of the second capacitor C2 to the fourth capacitor C4 determines the gain of the negative output voltage Voutn. In order to accurately reflect the voltage difference between the base and the emitter of the transistors BT 1-BT 4, the capacitance values of the first capacitor C1 and the second capacitor C2 are set to be the same, and the capacitance values of the third capacitor C3 and the fourth capacitor C4 are set to be the same.

In the embodiment, the first switch SW1, the third switch SW3, the fifth switch SW5 and the seventh switch SW7 are controlled by a control signal Φ 1, and the second switch SW2, the fourth switch SW4, the sixth switch SW6 and the eighth switch SW8 are controlled by a control signal Φ 2, wherein the control signals Φ 1 and Φ 2 are sequentially enabled during the temperature sensing period.

Further, during the first sensing period, the control signal Φ 1 is enabled first, and the control signal Φ 2 is disabled. At this time, the first switch SW1, the third switch SW3, the fifth switch SW5 and the seventh switch SW7 are turned on by the control signal Φ 1, and the second switch SW2, the fourth switch SW4, the sixth switch SW6 and the eighth switch SW8 are turned off by the control signal Φ 2. Accordingly, the charge stored in the first capacitor C1 is equal to (VREF-Vcm) × C1, the charge stored in the second capacitor C2 is equal to (VREF-VBE-Vcm) × C2, where VBE is the difference between the base and the emitter of the transistors BT1 to BT4, VREF is the reference voltage VREF, Vcm is the intermediate voltage Vcm, C1 is the capacitance value of the capacitor C1, and C2 is the capacitance value of the capacitor C2.

Then, in a second sensing period after the first sensing period, the control signal Φ 1 is disabled and the control signal Φ 2 is enabled. At this time, the first switch SW1, the third switch SW3, the fifth switch SW5 and the seventh switch SW7 are turned off by the control signal Φ 1, and the second switch SW2, the fourth switch SW4, the sixth switch SW6 and the eighth switch SW8 are turned on by the control signal Φ 2. Therefore, the voltage across the third capacitor C3 is equal to (VREF-Vcm) × C1/C3, and the voltage across the fourth capacitor C4 is equal to (VREF-VBE-Vcm) × C2/C4.

After the first sensing period and the second sensing period, the positive output voltage Voutp will be Vcm + (VREF-Vcm) C1/C3, and the negative output voltage Voutn will be Vcm + (VREF-VBE-Vcm) C2/C4. Since the capacitance of the first capacitor C1 is the same as the capacitance of the second capacitor C2 and the capacitance of the third capacitor C3 is the same as the capacitance of the fourth capacitor C4, the temperature-dependent voltage Vout1 is VBE × C1/C3. In the bipolar transistor, the voltage difference between the base and the emitter of the transistor is related to the ambient temperature, so that the change of the ambient temperature can be sensed through the change of the voltage difference between the base and the emitter of the transistor. Also, since the reference voltage terminal PVR is a known configuration in the sensing chip 100, the number of pins can be reduced.

In the embodiment, the bipolar devices are exemplified by bipolar transistors BT 1-BT 4, but in other embodiments, the bipolar devices may be implemented by diodes, and the embodiments of the present invention are not limited thereto. In addition, in the embodiment, a plurality of bipolar transistors BT 1-BT 4 are used, but in other embodiments, only a single bipolar transistor (e.g., BT 1-BT 4) may be provided, i.e., only a single sensing terminal (e.g., PS 1-PS 4) may be used, depending on the application environment. At this time, the negative sensing terminal NIN of the sense amplifying circuit 111 and the current source Cu1 can be directly coupled to the single sensing terminal (e.g., PS 1-PS 4) without configuring the multiplexer MX 1.

FIG. 2 is a circuit diagram of a temperature sensing circuit according to another embodiment of the present invention. Referring to fig. 1 and 2, the temperature sensing circuit 200 is substantially the same as the temperature sensing circuit 100, except for the bipolar transistors BT1 a-BT 4a, the current source Cu2 and the sense amplifier circuit 111a, wherein the same or similar elements are given the same or similar reference numerals. The current source Cu2 is coupled between the output of the multiplexer MX2 and the system high voltage OVDD.

In the embodiment, bases and collectors of the bipolar transistors BT1 a-BT 4a are respectively coupled to the corresponding sensing terminals PS 1-PS 4, and emitters of the bipolar transistors BT1 a-BT 4a are commonly coupled to the reference voltage terminal PVR to receive the regulated reference voltage VREF. Further, the base and the collector of the bipolar transistor BT1a are coupled to the sensing terminal PS1, and the base and the collector of the bipolar transistor BT2a are coupled to the sensing terminal PS2, which is shown in fig. 2 and will not be described herein.

The positive sensing terminal PIN of the sensing amplifying circuit 111a is coupled to one of the sensing terminals PS 1-PS 4 through the multiplexer MX1, and the negative sensing terminal NIN of the sensing amplifying circuit 111a is coupled to the reference voltage terminal PVR. The sense amplifier circuit 111 amplifies the reference voltage VREF and the voltage of one of the sense terminals PS1 to PS4, so that the positive sense output terminal POT and the negative sense output terminal NOT of the sense amplifier circuit 111 provide a positive output voltage Voutp and a negative output voltage Voutn, respectively, and the voltage difference between the positive output voltage Voutp and the negative output voltage Voutn is the temperature-dependent voltage Vout1 corresponding to one of the bipolar transistors BT1a to BT4 a.

Further, during the first sensing period, the charge stored in the first capacitor C1 is equal to (VBE + VREF-Vcm) × C1, the charge stored in the second capacitor C2 is equal to (VREF-Vcm) × C2, where VBE is the difference between the base and the emitter of the transistors BT 1-BT 4, VREF is the reference voltage VREF, Vcm is the intermediate voltage Vcm, C1 is the capacitance value of the capacitor C1, and C2 is the capacitance value of the capacitor C2.

In a second sensing period after the first sensing period, the voltage across the third capacitor C3 is equal to (VBE + VREF-Vcm) × C1/C3, and the voltage across the fourth capacitor C4 is equal to (VREF-Vcm) × C2/C4. After the first sensing period and the second sensing period, the positive output voltage Voutp is Vcm + (VBE + VREF-Vcm) × C1/C3, and the negative output voltage Voutn is Vcm + (VREF-Vcm) × C2/C4. In the embodiment, it is assumed that the capacitance of the first capacitor C1 is the same as that of the second capacitor C2 and the capacitance of the third capacitor C3 is the same as that of the fourth capacitor C4, so that the temperature-dependent voltage Vout1 is VBE × C1/C3.

In summary, the temperature sensing circuit according to the embodiment of the invention utilizes the reference voltage terminal of the sensing chip as the voltage source of the bipolar device to suppress the circuit interference through the voltage regulator. Therefore, the accuracy of temperature sensing can be improved without configuring additional terminals, thereby reducing hardware cost. Furthermore, the voltage across the bipolar element can be extracted by the differential amplifier circuit, so as to further suppress circuit noise.

Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.

Claims (10)

1. A temperature sensing circuit, comprising:

a sensing chip, comprising:

at least one sensing end;

a reference voltage terminal for providing a stabilized reference voltage;

a low voltage terminal for receiving a ground voltage;

a current source coupled to the at least one sensing terminal;

a sensing amplifying circuit coupled to the reference voltage terminal and the at least one sensing terminal for providing a temperature-dependent voltage;

at least one bipolar element having a positive terminal and a negative terminal, wherein the positive terminal is coupled to the reference voltage terminal and the negative terminal is coupled to the corresponding sensing terminal; and

a voltage stabilizing capacitor coupled between the reference voltage terminal and the ground voltage;

and the reference voltage end of the sensing chip is used as a voltage source of the bipolar element.

2. The temperature sensing circuit of claim 1, wherein the at least one bipolar element comprises at least one diode or at least one bipolar transistor.

3. The temperature sensing circuit of claim 1, wherein when the at least one sensing terminal comprises a plurality of sensing terminals, the sensing chip further comprises a multiplexer, wherein a plurality of input terminals of the multiplexer are coupled to the sensing terminals, and an output terminal of the multiplexer is coupled to the sense amplifying circuit for sequentially coupling the sense amplifying circuit to one of the sensing terminals.

4. The temperature sensing circuit of claim 1, wherein the sensing chip further comprises a voltage regulator coupled to the reference voltage terminal for providing the regulated reference voltage.

5. The temperature sensing circuit of claim 1, wherein a positive sense terminal of the sense amplifier circuit is coupled to the reference voltage terminal, a negative sense terminal of the sense amplifier circuit is coupled to the at least one sense terminal, and a positive sense output terminal and a negative sense output terminal of the sense amplifier circuit provide the temperature-dependent voltage.

6. The temperature sensing circuit of claim 5, wherein the sense amplifying circuit comprises:

a first capacitor;

a first switch coupled between the first end of the first capacitor and the reference voltage end;

a second switch coupled between the first end of the first capacitor and an intermediate voltage;

a second capacitor;

a third switch coupled between the first end of the second capacitor and the at least one sensing end;

a fourth switch coupled between the first end of the second capacitor and the intermediate voltage;

an operational amplifier having a positive input terminal, a negative input terminal, a positive output terminal coupled to the positive sensing output terminal, and a negative output terminal coupled to the negative sensing output terminal;

a fifth switch coupled between the second terminal of the first capacitor and the intermediate voltage;

a sixth switch coupled between the second end of the first capacitor and the positive input end;

a seventh switch coupled between the second end of the second capacitor and the intermediate voltage;

an eighth switch coupled between the second end of the second capacitor and the negative input terminal;

a third capacitor coupled between the positive input terminal and the positive output terminal; and

and the fourth capacitor is coupled between the negative input end and the negative output end.

7. The temperature sensing circuit of claim 6, wherein during a first sensing period, the first switch, the third switch, the fifth switch, and the seventh switch are turned on, and the second switch, the fourth switch, the sixth switch, and the eighth switch are turned off; and turning on the second switch, the fourth switch, the sixth switch and the eighth switch and turning off the first switch, the third switch, the fifth switch and the seventh switch in a second sensing period after the first sensing period.

8. The temperature sensing circuit of claim 1, wherein the sensing chip further comprises an analog-to-digital converter for receiving the temperature-dependent voltage to provide a temperature data.

9. A temperature sensing circuit, comprising:

a sensing chip, comprising:

at least one sensing end;

a reference voltage terminal;

a low voltage terminal for receiving a ground voltage;

a current source coupled to the at least one sensing terminal;

a voltage stabilizer coupled to the reference voltage terminal for providing a stabilized reference voltage to the reference voltage terminal;

a sense amplifier circuit, wherein a positive sense terminal of the sense amplifier circuit is coupled to the at least one sense terminal, a negative sense terminal of the sense amplifier circuit is coupled to the reference voltage terminal, and a positive sense output terminal and a negative sense output terminal of the sense amplifier circuit provide a temperature-dependent voltage;

at least one bipolar element having a positive terminal and a negative terminal, wherein the positive terminal is coupled to the corresponding sensing terminal, and the negative terminal is coupled to the reference voltage terminal; and

a voltage stabilizing capacitor coupled between the reference voltage terminal and the ground voltage;

and the reference voltage end of the sensing chip is coupled with the negative electrode end of the bipolar element.

10. The temperature sensing circuit of claim 9, wherein the at least one bipolar element comprises at least one diode or at least one bipolar transistor.

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