Abstract: An apparatus relating generally to a transmitter-side of a transceiver or a transmitter used to provide a clock signal is disclosed. In this apparatus, a first signal source is to provide a first periodic signal. A second signal source is to provide a second periodic signal. A first multiplexer is coupled to receive the first periodic signal and the second periodic signal to provide a selected one thereof as a first selected output. A phase interpolator is coupled to the first multiplexer to receive the first selected output. The phase interpolator includes a second multiplexer. The second multiplexer is coupled to receive the first selected output and a phase-interpolated version of the first selected output to output a selected one thereof as a second selected output. A divider is coupled to the second multiplexer to receive the second selected output to provide the clock signal.

Abstract: Circuits and methods are provided for estimating a latency through a FIFO buffer. A first detector detects first instances of a pattern in first data values serially written to a write port of the FIFO buffer. A second detector detects second instances of the pattern in second data values serially read from a read port of the FIFO buffer. The second data values are the first data values delayed by the latency through the FIFO buffer. A counter counts a count of active transitions of a sample clock signal. The counter starts on each detected first instance and stops on each detected second instances. The count provides an estimate of the latency of the FIFO buffer.