Receiverless detection schemes for optical clock distribution

This paper summarizes experiments using a modelocked laser to produce a fast-rising, low-jitter electrical signal for clocking CMOS circuits. A simple integrating optical-to-electrical conversion scheme using two photodiodes is used to minimize jitter, area and electrical power consumption. This scheme is called receiver-less because there is no receiver to introduce unwanted skew, jitter and electrical power consumption. Receiver-less optical clock injection to a single CMOS circuit with < 6 ps rms jitter has been demonstrated. To scale the receiver-less concept low capacitance detectors are necessary. Transit-time limited rise times from low capacitance monolithic silicon CMOS photo-detectors have been simulated using 425 nm short pulses. The utility of this ‘receiver-less’ scheme is examined for larger clock distribution networks and varying photodiode capacitances.