In operation, the delta-sigma ADC 100 may perform a sample-and hold function and an integration function in sequence. For example, and referring to FIGS. 2 and 3, during the sample-and hold function, the first switch 225 and the second switch 230 are closed (ON). While the first and second switches 225, 230 are closed, the first capacitor 210 charges according to the voltage of the input signal V_IN. After the first capacitor 210 is charged, the first and second switches 225, 230 are opened (OFF) to hold the charge of the first capacitor 210. In addition, the input terminal of the amplifier 200 provides a high impedance so that the charge is held in the first capacitor 210.

The integrator 110 may sum an output voltage from the second signal converter 125 and the voltage of the first capacitor 210 (i.e., a summed voltage).

During integration, the amplifier 200, the first capacitor 210, the second capacitor 205, and the resistor 220 operate together as an op-amp integrator circuit that generates an output voltage that is proportional to the integral of the summed voltage.