Track & Hold

This is a variation of a Sample & Hold. Both have two inputs – a gate signal, and a voltage reference signal – and a voltage output. When a Sample & Hold receives a gate high signal, it freezes and outputs the voltage reference coming into the reference input. This voltage is maintained until a new gate high signal; gate low signals are ignored. With a Track & Hold, when the gate is high, the reference input it passed along to the voltage output (this is the “tracking” phase); when the gate goes low, the input voltage at that instant is frozen and maintained at the voltage output until a new gate high signal is received.