A method for measuring capacitance may include integrating charge with a charge integrator having a charge integrator input and output, filtering, with a loop filter having a loop filter input coupled to the charge integrator output and having a loop filter output, a first signal generated at the charge integrator output, quantizing, with quantizer having a quantizer input coupled to the loop filter output and a having quantizer output, a second signal generated at the loop filter output, processing, with a first feedback path having a first feedback path input coupled to the quantizer output and a first feedback path output coupled to the charge integrator input, a low-frequency spectrum of a quantizer output signal, and processing, with a second feedback path having a second feedback path input coupled to the quantizer output and a second feedback path output coupled downstream in a signal path of the apparatus relative to the charge integrator, a high-frequency spectrum of the quantizer output signal.

A flash analog-to-digital converter (ADC) includes comparators that convert an analog input signal to a digital output signal. Offsets of these comparators introduce noise and can hurt the performance of the ADC. Thus, these comparators are calibrated using calibration codes. Conventional calibration methods determine these calibration codes by removing the ADC from an input signal. Otherwise, it is difficult to distinguish the noise from the signal in the calibration measurement. In contrast, an embodiment can determine the calibration codes while the ADC converts the input signal to a digital signal. Such an embodiment can be achieved by a frequency-domain technique. In an embodiment employing a frequency-domain power meter, an input signal can be removed from the power measurement. This removal enables accurate measurement of in-band noise without having the measurement be corrupted by input signal power.

A continuous-time sigma-delta modulator includes a continuous-time sigma-delta modulation module, a data monitoring module, and an offset calibration module. The data monitoring module and the offset calibration module are added on the basis of the continuous-time sigma-delta modulation module. Based on a hardware architecture design of the offset calibration module and the data monitoring module, with reference to software data processing, an offset of a quantizer in the continuous-time sigma-delta modulation module can be pre-calibrated based on feedback of a signal-to-noise ratio of a digital signal and a preset calibration algorithm, to obtain an offset calibration digital code. Finally, the offset calibration digital code is input into the quantizer by using the offset calibration module, and the offset of the quantizer is finally calibrated based on the offset calibration digital code.

The systems and methods discussed herein related to analog to digital conversion. An apparatus can include an analog to digital converter including a loop circuit and a comparator circuit. The apparatus can also include a first circuit configured to provide comparator offset calibration for the comparator circuit and a second circuit configured to provide loop calibration for the loop circuit.