Femtosecond-precision electronic clock distribution in CMOS chips with laser pulses

We demonstrated a femtosecond-precision clock distribution network (CDN) by injecting photocurrent pulses extracted from an optical frequency comb source into a driverless CDN in CMOS chips. Low-jitter and sharp-edged photocurrent pulses directly drive capacitive metal-mesh structure in a CMOS chip thus generating GHz-clock signal in the voltage domain. Femtosecond-level on-chip jitter and skew have been accomplished in conjunction with ultralow comb-jitter and clock-driverless structure. The inter-domain skew has been compensated in the optical paths by monitoring them with on-chip time-to-digital converter (TDC). When compared to conventional H-tree CDN, reduction of on-chip heat dissipation was observed.