И тем не менее, Analog Devices именно так и измеряют емкость: The AD5933 is a high precision impedance converter system solution that combines an on-board frequency generator with a 12-bit, 1 MSPS, analog-to-digital converter (ADC). The frequency generator allows an external complex impedance to be excited with a known frequency. The response signal from the impedance is sampled by the on-board ADC and a discrete Fourier transform (DFT) is processed by an on-board DSP engine. The DFT algorithm returns a real (R) and imaginary (I) data-word at each output frequency.
https://www.chipdip.ru/product/eval-ad5933ebz-ad5933-impedance-converter-analog-devices-8006120819