Shift-register-based clock phase interpolator

Abstract

An integrated circuit device includes functional circuitry, and serializer/deserializer circuitry for serial communication with the functional circuitry. The serializer/deserializer circuitry includes phase interpolator circuitry for interpolating phases of a clock signal of the integrated circuit device. The phase interpolator circuitry includes a phase shift register having storage locations configured to represent the phases of the clock signal, and phase rotation control circuitry configured to decode a phase code signal to determine a shifting direction for phase selections in storage locations of the phase shift register. The phase rotation control circuitry may be configured to determine the shifting direction based on only the most significant bit and the second most significant bit of the phase code signal. The phase interpolator circuitry may further include weight decoder circuitry configured to derive, from the phase code signal, interpolation weights to control combination of selected phases of the clock signal.