ADC offset DAC glitch suppression

A method for suppressing glitches in an analog-to-digital converter (ADC) circuit during an offset calibration process, comprising:

• performing the offset calibration process during mission mode by iteratively adjusting bias currents within source follower buffers of the ADC circuit to compensate for offset errors;
• receiving, at a current steering digital-to-analog converter (DAC) comprising a single-ended unit current cell comprising a positive switch and a negative switch that are independently controllable, a strobe signal used to update a calibration code of the offset calibration process;
• and
• in response to transitioning from an off state to an on state, using a precharge signal based on the strobe signal to precharge a tail node of the single-ended unit current cell before turning on the positive switch, thereby suppressing glitches caused by transients in the bias currents.

An analog-to-digital converter (ADC) circuit, comprising:

• one or more source follower buffers to receive an analog input signal;
• a comparator to process outputs of the one or more source follower buffers;
• a digital calibration finite state machine (FSM) to receive an output of the one or more source follower buffers and perform an offset calibration process during mission mode by iteratively adjusting bias currents within the at least one of the one or more source follower buffers to compensate for offset errors;
• a precharge signal generator to:
• receive a strobe signal used to update a calibration code of the offset calibration process;
• and
• generate a precharge signal based on the strobe signal;
• and
• a current steering digital-to-analog converter (DAC), comprising a single-ended unit current cell comprising a positive switch and a negative switch that are independently controllable, to:
• in response to transitioning from an off state to an on state, use the precharge signal to precharge a tail node of the single-ended unit current cell before turning on the positive switch, thereby suppressing glitches caused by transients in the bias currents.