A sub-400 fJ/bit thermal tuner for optical resonant ring modulators in 40 nm CMOS

Optical ring modulators are highly susceptible to external temperature noise and to self-heating from absorbed optical power. We mitigate both problems through circuit techniques. A control loop at the ring measures output power and controls a local heater to compensate for external temperature noise. A control loop at the receiver dynamically tracks DC variations to compensate for self-heating effects. The design has been implemented in a 40 nm TSMC technology.