Digital “assist” circuits can improve the efficiency of traditionally analog circuit blocks, especially as technologies scale to the detriment of analog blocks. We apply some of these techniques to a 10 Gbps optical reciever, and demonstrate 395 fJ/b energy efficiency. Digital calibration blocks wrapped around a simple analog core enabled offset compensation, TIA biasing, and DLL re-timing, and cost negligible performance and power overhead. The assist circuits cost around 40% area overhead.