US Patent 11509319 Low integral non-linearity digital-to-time converter for fractional-N PLLS

An apparatus includes a first digital-to-time converter (DTC) and a second DTC. The first DTC includes a sequence of delay stages. Each of the delay stages adds a delay to an input signal based on a control signal. Each delay stage includes a comparator and a capacitor coupled to an input of the comparator and to ground. The second DTC is coupled in parallel to the first DTC. The second DTC adds a delay to the input signal based on a complement of the control signal.