Abstract
An electronic circuit for online monitoring a clock signal is provided. The electronic circuit includes a period-to-pulse converter, a pulse-shrinking block and an encoder. The period-to-pulse converter receives the clock signal outputted by a phase-locked loop, and converts each of a plurality of clock period samples of the clock signal to generate a pulse-train signal having a plurality of pulses. The pulse-shrinking block receives the plurality of pulses of the pulse-train signal, and generates a plurality of catch bits by shrinking the plurality of pulses of the pulse-train signal. The encoder outputs a minimum code denoting a minimum clock period of the clock signal and a maximum code denoting a maximum clock period of the clock signal according to the plurality of catch bits. The electronic circuit subtracts the maximum code and the minimum code to generate a peak-to-peak jitter amount code.