Timing margin is an
electronics
The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...
term that defines the difference between the actual change in a
signal
In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...
and the latest time at which the signal can change in order for an electronic
circuit to function correctly. It is used in the design of
digital electronics
Digital electronics is a field of electronics involving the study of digital signals and the engineering of devices that use or produce them. This is in contrast to analog electronics and analog signals.
Digital electronic circuits are usual ...
.
Illustration
In this image, the lower signal is the clock and the upper signal is the data. Data is recognized by the circuit at the positive edge of the clock. There are two time intervals illustrated in this image. One is the
setup time
In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information – a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and ...
, and the other is the timing margin. The setup time is illustrated in red in this image; the timing margin is illustrated in green.
The edges of the signals can shift around in a real-world electronic system for various reasons. If the clock and the data signal are shifted relative to each other, this may increase or reduce the timing margin; as long as the data signal changes before the setup time is entered, the data will be interpreted correctly. If it is known from experience that the signals can shift relative to each other by as much as 2 microseconds, for instance, designing the system with at least 2 microseconds of timing margin will prevent incorrect interpretation of the data signal by the receiver.
If the physical design of the circuit is changed, for example by giving more wire that the clock signal is transmitted on, the edge of the data signal will move closer to the positive edge of the clock signal, reducing the timing margin. If the signals have been designed with enough timing margin, only the correct data will be received.
Electrical engineering
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