Digitally assisted feedback loop for duty-cycle correction in an injection-locked pll

Abstract

We disclose a system, which performs a duty-cycle correction operation for an injection-locked phase-locked loop (PLL). The system first obtains a pattern of positive and negative error pulses at rising and falling edges of a reference clock signal for the injection-locked PLL, wherein the pattern specifies deviations of the reference clock signal from a 50% duty cycle. The system multiplies the pattern of positive and negative error pulses by a duty-cycle distortion (DCD) template, which specifies a sign of a duty-cycle error for the reference clock signal, to calculate duty-cycle distortion values. The system then accumulates the duty-cycle distortion values to produce a duty-cycle-error amplitude. Next, the system multiplies the duty-cycle-error amplitude by the DCD template to produce a duty-cycle correction signal. Finally, the system uses the duty-cycle correction signal to compensate for timing errors in the injection-locked PLL, which are caused by duty-cycle variations in the reference clock signal.