Abstract: An example circuit includes: a transmitter configured to transmit a clock pattern based on a transmit clock; a receiver, coupled to the transmitter, configured to sample the clock pattern based on a receive clock to generate a bit pattern, where there is a non-zero frequency difference between the transmit clock and the receive clock; a phase interpolator (PI) configured to add a phase shift to a source clock to supply one of the transmit clock or the receive clock; and a test circuit configured to apply adjustments to the phase shift over a time period and determine a phase distribution of the PI based on changes in the bit pattern over the time period.

Abstract: A circuit for receiving data is described. The circuit comprises a phase detector circuit comprising a detector having a first input configured to receive a sum of an oscillator phase and a phase error, and a second input coupled to an output of a first sample selector; a second sample selector having an input coupled to receive the input data and generate output data; and an eye detection circuit comprising a third sample selector having an input coupled to receive the input data and a comparator for comparing outputs of the second sample selector and the third sample selector to determine how much an eye is open for a plurality of channels. A method of implementing a receiver is also described.