SAR ADC using single-capacitor pulse width to analog converter based DAC

This work presents a SAR ADC using single-capacitor pulse width to analog converter based DAC. In the proposed scheme, the single-capacitor DAC is realized by partially charging or discharging the sampling capacitor with a DC reference current. The charge and discharge time is determined by the pulse width of the control signal. As a result, a SAR ADC can be realized by using a single-capacitor, current source, current mirror, comparator, and control logic, which can significantly reduce the circuit area and simplifies the switch control scheme compared to conventional SAR ADCs using capacitor DACs. A 6-bit SAR ADC is designed using CMOS 0.35μm technology where the operation is verified through circuit level simulations.