brief introduction: Introduction:Sample-and-hold (SH) is part of the analog-to-digital conversion process. The core circuitry of an ADC requires a static input voltage during the small interval of time that is needed to convert the analog signal into a digital value. The SH device (or block in the case of an integrated circuit) provides that static input to the ADC while the actual input signal continues to change. Typical SH circuits use operational amplifiers (op-amps) with very large input impedances to sense th