Abstract: Certain aspects of the present disclosure provide methods and apparatus for performing background noise estimation using a circular histogram noise figure (CHNF) in an analog-to-digital converter (ADC) circuit with redundancy. The estimated noise may be used to reduce the noise (e.g., comparator noise) in the ADC circuit. One example ADC circuit generally includes at least one of a comparator or a digital-to-analog converter (DAC) and at least one digital feedback input. The at least one digital feedback input is coupled to the at least one of the comparator or the DAC and is configured to adjust at least one parameter of the at least one of the comparator or the DAC based on at least a portion of an output of the ADC circuit.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for calibrating time-interleaved analog-to-digital converter (ADC) circuits and generating a suitable signal for such calibration. Certain aspects provide a signal generator for calibrating a time-interleaved ADC circuit having a plurality of channels. The signal generator generally includes a pattern generator configured to receive a periodic signal and to output a bitstream based on the periodic signal and a conversion circuit having an input coupled to an output of the pattern generator and configured to generate a waveform based on the bitstream. The bitstream has a bit pattern with a total number of bits that shares no common factor with a number of the channels and includes a relatively lower frequency component combined with a relatively higher frequency component.

Abstract: Certain aspects of the present disclosure provide apparatus and techniques for analog-to-digital conversion using a time-to-digital converter (TDC). For example, certain aspects provide a quantizer using a TDC. The quantizer may include at least one first capacitive element and a set of switches configured to selectively couple a first terminal and a second terminal of the at least one first capacitive element to at least one input voltage source. The TDC may also include a reference voltage source, at least one switch coupled between the second terminal of the at least one first capacitive element and an output of the reference voltage source, a current source selectively coupled to the first terminal of the at least one first capacitive element, and a voltage sense circuit coupled to the first terminal of the at least one first capacitive element.