TEMPERATURE DRIFT COMPENSATION

• US 20180292852A1
• Filed: 03/22/2018
• Published: 10/11/2018
• Est. Priority Date: 04/07/2017
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: KRISHNAN, Sandeep Shylaja
• Granted Patent: US 10,545,522 B2
• Time in Patent Office: Days
• CPC Class Codes: G05F 1/468 characterised by reference voltage circuitry, e.g. soft start, remote shutdown
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit
• CPC Class Codes: H03M 1/089 of temperature variations

Abstract

A voltage reference circuit includes a bandgap circuit and a temperature compensation circuit. The temperature compensation circuit includes a first trim circuit, a second trim circuit, and a resistive digital-to-analog converter. The resistive digital-to-analog converter is coupled to the first trim circuit, the second trim circuit, and the bandgap circuit. The resistive digital-to-analog converter is configured to generate a temperature compensation voltage, and to provide the temperature compensation voltage to the bandgap circuit.

Claims

1. A voltage reference circuit, comprising:

a bandgap circuit; and

a temperature compensation circuit, comprising;

a first trim circuit;

a second trim circuit;

a first resistive digital-to-analog converter coupled to the first trim circuit, the second trim circuit, and the bandgap circuit;

the first resistive digital-to-analog converter configured to;

generate a temperature compensation voltage; and

provide the temperature compensation voltage to the bandgap circuit.

2. The voltage reference circuit of claim 1, wherein the first trim circuit comprises a proportional to absolute temperature voltage generation circuit and a second resistive digital-to-analog converter.

3. The voltage reference circuit of claim 2, wherein an output terminal of the second resistive digital-to-analog converter is coupled to an input terminal of the first resistive digital to analog converter.

4. The voltage reference circuit of claim 2, wherein the proportional to absolute temperature voltage generation circuit is configured to generate a voltage proportional to absolute temperature as a function of output of the bandgap circuit.

5. The voltage reference circuit of claim 2, wherein the proportional to absolute temperature voltage generation circuit is configured to generate a voltage proportional to absolute temperature as output voltage of the bandgap circuit less three diode drop voltages.

6. The voltage reference circuit of claim 1, wherein the second trim circuit comprises a complementary to absolute temperature voltage generation circuit and a third resistive digital-to-analog converter.

7. The voltage reference circuit of claim 6, wherein an output terminal of the third resistive digital-to-analog converter is coupled to an input terminal of the first resistive digital to analog converter.

8. The voltage reference circuit of claim 6, wherein the complementary to absolute temperature voltage generation circuit is configured to generate a voltage complementary to absolute temperature as a function of output of the bandgap circuit.

9. The voltage reference circuit of claim 6, wherein the complementary to absolute temperature voltage generation circuit is configured to generate a voltage complementary to absolute temperature as two diode drop voltages.

10. The voltage reference circuit of claim 1, wherein the first resistive digital-to-analog converter is configured to set a rate of change of the temperature compensation voltage with temperature, the rate of change selected to compensate for a rate of change of voltage in the bandgap circuit.

11. A method for trimming a voltage reference circuit, comprising:

adjusting an output voltage of a bandgap circuit to a reference voltage at a first temperature;

generating a temperature compensation voltage to adjust the output voltage as a function of temperature, the generating comprising setting a first resistive digital-to-analog converter to produce a weighted sum of a voltage proportional to absolute temperature and a voltage complementary to absolute temperature; and

providing the temperature compensation voltage to the bandgap circuit to adjust the output voltage.

12. The method of claim 11, further comprising generating the voltage proportional to absolute temperature as the output voltage less three diode drop voltages.

13. The method of claim 11, further comprising generating the voltage complementary to absolute temperature as two diode drop voltages.

14. The method of claim 11, further comprising setting a second resistive digital-to-analog converter to scale the voltage proportional to absolute temperature to the reference voltage at the first temperature.

15. The method of claim 14, further comprising opening a switch disposed between the first resistive digital-to-analog converter and a third resistive digital-to-analog converter while setting the second resistive digital-to-analog converter.

16. The method of claim 14, further comprising setting a third resistive digital-to-analog converter to scale the voltage complementary to absolute temperature to the reference voltage at the first temperature.

17. The method of claim 16, further comprising opening a switch disposed between the first resistive digital-to-analog converter and the second resistive digital-to-analog converter while setting the third resistive digital-to-analog converter.

18. The method of claim 11, further comprising opening a switch to disconnect the first resistive digital-to-analog converter from the bandgap circuit while adjusting the output voltage of the bandgap circuit

19. A temperature compensation circuit, comprising:

a bandgap circuit;

a proportional to absolute temperature voltage generation circuit;

a complementary to absolute temperature voltage generation circuit;

a first resistive digital-to-analog converter coupled to an output of the proportional to absolute temperature voltage generation circuit;

a second resistive digital-to-analog converter coupled to an output of the complementary to absolute temperature voltage generation circuit;

a third resistive digital-to-analog converter coupled to;

an output of the first resistive digital-to-analog converter;

an output of the second resistive digital-to-analog converter; and

an input of the bandgap circuit.

20. The voltage reference circuit of claim 19, further comprising:

a first switch that connects the first resistive digital-to-analog converter to the third resistive digital-to-analog converter;

a second switch that connects the second resistive digital-to-analog converter to the third resistive digital-to-analog converter; and

a third switch that connects the third resistive digital-to-analog converter to the bandgap circuit.