Clock Domain Crossing

 A clock domain crossing occurs whenever data is transferred from a flop driven by one clock to a flop driven by another clock.

Fig : Clock domain Crossing

Two Flop Synchronizer

Two flop synchronizer is used for synchronizing a single bit level signal. It converts the signal from source clock domain to destination clock domain.

Two stage flop synchronizer is shown below:

Fig : Two flop synchronizer

Slow to Fast Pulse Synchronizer

Fast to Slow Pulse Synchronizer

Handshake Synchronizer