Asymmetric locking technique for asymmetric frequency locked loop

A system that generates a click signal includes a first digitally controlled oscillator (DCO) having a first fundamental frequency, and a second DCO having a second fundamental frequency. The system also includes a Muller C-element, which combines outputs of the first and second DCOs to produce the clock signal, which feeds back into the first and second DCOs. During a calibration operation, while the second DCO is set to a frequency larger than the target frequency, the system adjusts the first DCO with reference to a first feedback loop, which includes the first DCO, so that the clock signal matches the target frequency, and while the first DCO is set to the adjusted first fundamental frequency plus a frequency offset, the system adjusts the second DCO with reference to a second feedback loop, which includes the second DCO, so that the clock signal matches the target frequency.