Sub-rate phase interpolator based clock data recovery architecture with phase skew correction

Abstract

A sub-rate (such as half-rate I and Q) phase-interpolator based CDR architecture is configured to receive serial data signals and multiple sub-rate clock signals (such as generated by a VCO either integrated or external). The CDR includes multiple phase interpolators to generate, from respective sub-rate clock signals, respective PI (phase-interpolated) sub-rate clock signals. A CDR loop is configured to receive the input data and the PI sub-rate clock signals, and to generate multiple PI control signals, each to control a respective phase interpolator to align the PI sub-rate clock signals to the data edges. A skew-correction loop includes skew detection circuitry to generate a skew error signal from the PI sub-rate clock signals corresponding to a skew error between the PI sub-rate clock signals, and skew-correction offset circuitry to generate, from the skew error signal, a skew-correction offset signal to modify a selected PI control signal.