Sample and Hold
You may have heard of the term sample rate in regards to audio. This is a big part of how we create digital audio from an analog signal. During recording, samples of the audio are taken to measure how much amplitude it has at a given point in time. Then when these samples are played back at the same rate it reproduces what we recorded. Most audio is recorded at 44,100 samples per second because this was determined to be the minimum resolution required to accurately reproduce the upper range of human hearing (20,000 Hz) according to something called the Nyquist theorem.
Sample and hold follows a similar principal, only in this case we are able to vary the sample rate, and the samples are output as voltages. Whenever a gate signal is received, a sample is captured of the source’s current voltage level.