Apple Inc.
METHOD AND APPARATUS FOR STOCHASTIC RING OSCILLATOR TIME-TO-DIGITAL CONVERTER WITH INTERLEAVED LOOP COUNTERS

Abstract:

A method and apparatus for generating a digital signal indicating a time between a start and a stop signal, including a short inverter ring operable to generate a clock signal. The clock signal is provided to a time-interleaved counter array that distributes the clock signal on a plurality of clock outputs as interleaved clock signals. Each interleaved clock signal is provided to a counter that counts a partial count value. The partial count values are combined to obtain a total count value as the digital signal indicating the time. A fine resolution signal is obtained from a chain of stochastic flip flops connected to outputs of the inverters in the short inverter ring. Multiple clock signal outputs of the inverter ring may be provided to multiple interleaved counters.