In the field of optical communications, the need to remove jitter from a Synchronous
Digital Hierarchy (SDH) or Synchronous Optical NETwork (SONET) datastream is recognized.
Consequently, the present invention provides a First-In-First-Out (FIFO) buffer
having a read-out clock frequency that is controlled in response to a depth error
of the FIFO buffer. The control of the read-out clock frequency is achieved by
a hardware control loop coupled to the FIFO buffer. The period of the control loop
is a product of the frequency at which the depth error of the FIFO buffer is acquired
and another factor. The another factor is the number of states of logic employed
by the control loop raised to an integer power.