One commonly used circuit is a flip-flop circuit. A flip-flop is used in a wide range of applications such as, for example, microprocessors, memory devices and registers.
One performance parameter of a flip-flop circuit is the insertion delay. The insertion delay is the sum of the set-up time and the propagation delay. The set-up time is the duration of time that input data into the flip-flop must be held steady before a clock edge so that the data is reliably sampled by the clock. The propagation delay is the time required from the clock transition for the output signal to change state. The insertion delay is a measure of how much of the clock cycle time is consumed by the flip-flop circuit.
Another performance parameter is the clock loading. The operation of a flip-flop circuit is driven by the clock, and a single chip can contain many flip-flops, often of the order of thousands. The clock may constitute a proportion of the power used by a circuit. Due to the large numbers of flip-flops used on a single chip, a flip-flop design with a reduced clock loading may lead to a chip with a reduced power consumption.