Comparator diagnostic systems and methods
An analog front-end circuit for self-calibrating a comparator, the circuit comprising a comparator in a comparator measurement path; a preamplifier coupled to the comparator by a set of switches; and an amplifier coupled to the preamplifier, the preamplifier receiving a reference signal as a first input and a user-definable reference as a second input, the user-definable reference generating a user-definable value chosen to create a known condition at an output of the preamplifier, the preamplifier determines a residual value that represents a measurement error in a signal path comprising the comparator and is used to adjust the user-definable reference value to calibrate the signal path such that threshold boundaries for the comparator can be adjusted to tighten a comparator specification.
1. An analog front-end circuit for self-calibrating a comparator, the circuit comprising:
a comparator in a comparator measurement path;
a preamplifier coupled to the comparator by a set of switches; and
an amplifier coupled to the preamplifier, the preamplifier receiving a reference signal as a first input and a user-definable reference as a second input, the user-definable reference generating a user-definable value chosen to create a known condition at an output of the preamplifier, the preamplifier determines a residual value that represents a measurement error in a signal path comprising the comparator and is used to adjust the user-definable reference value to calibrate the signal path such that threshold boundaries for the comparator can be adjusted to tighten a comparator specification.
2. The circuit according to claim 1 , further comprising one or more switches configured to decouple the preamplifier from the comparator to perform a calibration operation.
3. The circuit according to claim 1 , wherein the reference signal and an ADC are decoupled from the preamplifier in regular operation.
4. The circuit according to claim 1 , further comprising a programmable data register that generates a digital input word.
5. The circuit according to claim 1 , further comprising a register that stores the measurement error.
6. The circuit according to claim 1 , further comprising a reference voltage buffer that generates the reference signal as an analog voltage.
7. The circuit according to claim 1 , further comprising a DAC that, in a diagnostic phase, receives the reference signal.
8. The circuit according to claim 7 , wherein the DAC generates the user-definable reference.
9. The circuit according to claim 1 , wherein the user-definable value when multiplied by a first input gain of the preamplifier is substantially equal to the amplifier output multiplied by a second input gain of the preamplifier.
10. A method for self-calibrating a comparator in an analog front-end circuit, the method comprising:
providing a reference as a first input to an amplifier;
providing a user-definable reference value as a second input to the amplifier, the user-definable reference value chosen to create a known condition at an output of a preamplifier;
measuring the output of the preamplifier to determine a residual value that represents a measurement error in a comparator signal path;
based on the residual value, adjusting the user-definable reference value to calibrate the comparator signal path; and
changing threshold boundaries for a comparator to tighten a specification for the comparator.
11. The method according to claim 10 , wherein the user-definable reference is used to define or trigger at least one of an overvoltage threshold or an undervoltage threshold.
12. The method according to claim 10 , wherein the user-definable reference is used to define or trigger a component failure alert.
13. The method according to claim 10 , further comprising, in regular operation, decoupling an ADC in the analog front-end circuit and the reference from the amplifier.
14. The method according to claim 13 , further comprising, using the ADC to test an accuracy of the comparator and perform on-demand calibration to improve comparator accuracy and performance.
15. The method according to claim 10 , further comprising decoupling the preamplifier from the comparator to perform a calibration operation.
16. The method according to claim 10 , further comprising storing the measurement error in a register.
17. The method according to claim 10 , further comprising, in a diagnostic phase, providing the reference signal to a DAC that generates the user-definable reference.
18. The method according to claim 17 , wherein the user-definable value when multiplied by a first input gain of the preamplifier is substantially equal to the amplifier output multiplied by a second input gain of the preamplifier.
19. The method according to claim 10 , further comprising using a reference voltage buffer that generates the reference signal as an analog voltage.
20. The method according to claim 19 , further comprising automatically changing the user-definable reference value from an initial value.