Diagnostic circuits and methods for analog-to-digital converters

Apparatus comprising:

• a first ADC configured to convert an analog signal to a first digital signal;
• a second ADC configured to convert the analog signal to a second digital signal;
• a comparator having a first input responsive to the first digital signal, a second input responsive to the second digital signal, and an output at which a comparison signal is provided;
• and
• an output checker configured to process the comparison signal to generate a fault indicative of whether a fault has occurred in the ADC.

Apparatus comprising:

• a first ADC configured to convert a first analog signal to a first digital signal;
• a second ADC configured to convert a second analog signal to a second digital signal;
• an analog summation circuit responsive to the first analog signal and the second analog signal and configured to generate a first analog summation signal as a sum of the first analog signal and the second analog signal;
• a digital summation circuit responsive to the first digital signal and the second digital signal and configured to generate a digital summation signal as a sum of the first digital signal and the second digital signal;
• a digital-to-analog convertor (DAC) configured to convert the digital summation signal to a second analog summation signal;
• and
• a comparator having a first input responsive to the first analog summation signal, a second input responsive to the second analog summation signal, and an output at which a comparison signal is provided.

A method comprising:

• converting a first analog signal to a first digital signal with a first ADC;
• converting a second analog signal to a second digital signal with a second ADC;
• generating a first analog summation signal as a sum of the first analog signal and the second analog signal;
• generating a digital summation signal as a sum of the first digital signal and the second digital signal;
• converting the digital summation signal to a second analog summation signal;
• and
• comparing a first signal based on the analog summation signal to a second signal based on the second analog summation signal to generate a comparison signal.

Apparatus comprising:

• a sensing element configured to generate an analog input signal indicative of a parameter to be sensed;
• an offset cancellation circuit coupled to receive the analog input signal and configured to remove an offset associated with the analog input signal;
• a test circuit coupled to receive the analog input signal and configured to combine a test signal with the analog input signal to generate a combined signal, wherein the test circuit is substantially identical to the offset cancellation circuit;
• an ADC having an input coupled to receive the combined signal and an output at which a digital signal is provided;
• a recovery circuit configured to process the digital signal to recover the test signal;
• and
• a checker circuit configured to determine if an error has occurred in the ADC based on the recovered test signal.