US Patent 11569804 INL detection and calibration for phase-interpolator

An apparatus includes control logic coupled to a phase detector circuit and an adjustable delay circuit. The control logic is configured to obtain a state of a first phase of an output signal of a phase interpolator relative to a second phase of a reference signal, and adjust a delay of the reference signal until the second phase matches the first phase. The control logic is further configured to measure a total delay of the reference signal when the second phase matches the first phase, and determine integral non-linearity of the phase interpolator at the first code based on the total delay. The control logic may further calibrate a first code of a phase interpolator based, at least in part, on the integral non-linearity.