Sample and hold

Overview

The term "sample and hold" is used to describe a circuit that can "take a snapshot" of a continuously changing input voltage and output that continuously for a brief time.

Basics

In order to record information in a form that a binary computer can process; the information must: a.) not be changing in value and b.) be of a finite resolution. The process of assigning a value of finite resolution is called quantization. Audio is typically transmitted between pieces of equipment as a voltage waveform that is constantly changing over time. It will have a finite voltage range; so as long as the quantization is sufficiently "fine" in resolution, the voltage steps generated in the decoding process will be a close enough approximation of the original analog voltage waveform to produce minimum distortion. But how can a continuously changing voltage be measured? By using a sample and hold circuit.