A 4-Channel 1.25–10.3 Gb/s Backplane Transceiver Macro With 35 dB Equalizer and Sign-Based Zero-Forcing Adaptive Control

A 4-channel 1.25-10.3 Gb/s backplane transceiver macro with an adaptive analog linear equalizer (LE) and 1-tap speculative decision-feedback equalizer (DFE) receiver (Rx) and a 3-tap pre-emphasis transmitter (Tx) is presented. The equalizers cancel 15.7-35.8 dB loss at the half-rate frequency for 10.3 Gb/s transmission over 5-75 cm FR4 backplane with fixed Tx parameters. Rx equalizer parameters are adapted by sign-based zero-forcing (S-ZF), which is applicable to any LE circuit and implemented in simple logic. The adaptive control circuit has a pattern-tolerant feature which prevents the adapted equalizer parameters from drifting for non-random data. The macro is fabricated in 90 nm CMOS technology. A Tx/Rx pair occupies 0.380 mm² and consumes 260 mW from 1.2 V at 10.3 Gb/s per channel.