A Single-Ended NRZ Receiver With Gain-Enhanced Active-Inductive CTLE and Reference-Selection DFE for Memory Interfaces

We have proposed an 18-Gb/s single-ended receiver with gain-enhanced active-inductive (GE-AI) continuous-time linear equalizer (CTLE) and reference-selection (RS) decision-feedback equalizer (DFE). The proposed equalizers were optimized for single-ended memory interfaces. The GE-AI CTLE amplified the signal swing and obtained a boost factor from shunt peaking. In addition, it eliminated a single-to-differential amplifier (S2D) and amplifying stage from the analog front-end (AFE). The RS DFE extended the sampling margin without a current source for power saving without bandwidth reduction of the data path. A faster DFE loop delay was achieved with direct feedback from the comparator output to the RS MUX. The proposed receiver is the first work to employ the single-ended CTLE and DFE simultaneously. The implemented receiver equalizers compensated for the -15-dB channel loss at 18 Gb/s. Optimized for the single-ended memory interfaces, the receiver achieved the highest energy efficiency of 0.14 pJ/bit and the best figure-of-merit (FoM) of 0.009 pJ/bit/dB compared with the latest receivers.