Systems and methods for monitoring and compensation of analog to digital converter reference voltages

Patent metadata

Field	Value
Publication number	US-9564914-B1
Application number	US-201615079521-A
Country	US
Kind code	B1
Filing date	Mar 24, 2016
Priority date	Mar 24, 2016
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

The present disclosure provides systems and methods for identifying changes in and failures of a reference voltage of an analog to digital (A/D) converter. A non-scalar function of the reference voltage of the A/D converter can be determined and output to the A/D converter. The A/D converter is configured to output a digital value to the A/D conversion system, wherein the digital value corresponds to the non-scalar function of the reference voltage. The A/D conversion system decodes the non-scalar function of the reference voltage with a corresponding inverse function, and may determine the drift factor associated with the reference voltage. The A/D conversion system can report a change in, or a failure of, the A/D converter or its reference voltage, and can operate or prevent operation of protection elements.

First claim

What is claimed:

1. An analog to digital (A/D) conversion system, comprising:
an A/D converter;
a calibrated reference module to identify a calibrated voltage reference value, V refCAL , associated with the A/D converter;
a non-scalar module to receive a reference voltage, V ref , wherein the reference voltage, V ref , corresponds to the calibrated reference voltage, V refCAL , multiplied by a drift factor, α, such that V ref =αV refCAL , and wherein the non-scalar module outputs a non-scalar function of the reference voltage, N(V ref ), to the A/D converter;
a drift factor module to identify an inverse function of the non-scalar function and to calculate the drift factor, α, based on an inverse function of a first digital value, V dig , output by the A/D converter and corresponding to the non-scalar function of the reference voltage, N(V ref ), wherein the first digital value, V dig , corresponds to a ratio of the calibrated voltage reference value, V refCAL , and the reference voltage, V ref , such that the first digital value, V dig , can be expressed as the non-scalar function of the calibrated reference voltage multiplied by the drift factor divided by the drift factor, such that

V
dig

=

N
⁡

(

α
⁢

⁢

V
ref

)

α

;

and
an adjustment module to adjust at least one voltage value associated with the A/D converter using the calculated drift factor, α.

2. The A/D conversion system of claim 1 , wherein the at least one voltage value associated with the A/D converter comprises the reference voltage, V ref .

3. The A/D conversion system of claim 1 , wherein the at least one voltage value associated with the A/D converter comprises a digital output value corresponding to an input signal received by the A/D converter.

4. The A/D conversion system of claim 1 , wherein the at least one voltage value associated with the A/D converter comprises an input signal adjusted prior to reception of the input signal by the A/D converter.

5. The A/D conversion system of claim 1 , wherein the A/D converter comprises a bipolar capable A/D converter and wherein the non-scalar module comprises shifting the reference voltage by constant voltage.

6. The A/D conversion system of claim 1 , wherein the non-scalar module comprises a logarithmic amplifier.

7. The A/D conversion system of claim 1 , wherein the non-scalar module comprises an exponential amplifier.

8. The A/D conversion system of claim 1 , wherein the non-scalar module comprises an analog multiplier.

9. The A/D conversion system of claim 1 , wherein the non-scalar module comprises a non-linear element and wherein the non-scalar function comprises a non-linear module.

10. A method, comprising:
identifying a calibrated voltage reference value, V refCAL , associated with an analog to digital (A/D) converter;
receiving, via a non-scalar element, a reference voltage, V ref , wherein the reference voltage, V ref , corresponds to the calibrated reference voltage, V refCAL , multiplied by a drift factor, α, such that V ref =αV refCAL ,
generating, via the non-scalar element, a non-scalar function of the reference voltage, N(V ref );
receiving the non-scalar function of the reference voltage, N(V ref ), via the A/D converter;
outputting, via the A/D converter, a first digital value, V dig , corresponding to the non-scalar function of the reference voltage, N(V ref ), wherein the first digital value, V dig , of the non-scalar function of the reference voltage, N(V ref ), corresponds to a ratio of the calibrated voltage reference value, V refCAL , and the reference voltage, V ref , such that the first digital value, V dig , can be expressed as the non-scalar function of the calibrated reference voltage multiplied by the drift factor divided by the drift factor, such that

V
dig

=

N
⁡

(

α
⁢

⁢

V
ref

)

α

;

identifying an inverse function of the non-scalar function;
calculating the drift value, α, based on the inverse function of the first digital value, V dig ; and
adjusting at least one voltage value associated with the A/D converter using the calculated drift value, α.

11. The method of claim 10 , wherein the non-scalar function corresponds to a logarithmic function.

12. The method of claim 10 , wherein the non-scalar function corresponds to an exponential function.

13. The method of claim 10 , wherein adjusting the at least one voltage value associated with the A/D converter comprises adjusting the reference voltage, V ref .

14. The method of claim 10 , wherein adjusting the at least one voltage value associated with the A/D converter comprises adjusting a digital output value corresponding to an input signal received by the A/D converter.

15. The method of claim 10 , wherein adjusting the at least one voltage value associated with the A/D converter comprises adjusting an input signal prior to reception of the input signal by the A/D converter.

16. The method of claim 10 , wherein the A/D converter comprises a bipolar capable A/D converter and wherein the non-scalar element comprises shifting the reference voltage by constant voltage.

17. The method of claim 10 , wherein the non-scalar element comprises a logarithmic amplifier.

18. The method of claim 10 , wherein the non-scalar element comprises an exponential amplifier.

19. The method of claim 10 , wherein the non-scalar element comprises an analog multiplier.

20. The method of claim 10 , wherein the non-scalar element comprises a non-linear element and wherein the non-scalar function comprises a non-linear element.

21. A method for reporting a change in a reference voltage of an analog to digital (A/D) converter, comprising:
determining a calibrated value of a reference voltage of an A/D converter;
determining a first input of the A/D converter, wherein the first input of the A/D converter is an operating value of the reference voltage of the A/D converter adjusted according to a first non-scalar function;
comparing the first input of the A/D converter and the cal

Assignees

• Schweitzer Engineering Lab Inc

Inventors

• Mallett Travis C
• Armstrong Ben M

Classifications

• H03M1/1009 Primary

  Calibration · CPC title

• H03M1/34

  Analogue value compared with reference values (H03M1/48 takes precedence) · CPC title

• H03M1/109

  for DC performance, i.e. static testing (H03M1/1085 takes precedence) · CPC title

• H03M1/1038 Primary

  by storing corrected or correction values in one or more digital look-up tables (H03M1/1057 takes precedence) · CPC title

• H03M1/12

  Analogue/digital converters ({H03M1/001 – } H03M1/10 take precedence) · CPC title