A 1.89 mW/Gbps SST transmitter with three-tap FFE and impedance calibration

Abstract

This study presents an 8 Gbps low-power source-series terminated (SST) transmitter for high-speed serial links. The proposed transmitter consists of a novel hybrid 20:2 multiplexer followed by a three-tap feed-forward equalizer (FFE) and a shunt path SST driver. In addition, a high-precision impedance calibration circuit with slice unit replication is proposed to match the characteristic impedance of channel, whose maximum calibration error is 0.002%. Fabricated in 55-nm CMOS technology and has area of 0.024 mm². Measurement results show that the transmitter achieves data rate of 8 Gbps while maintaining good performance. The transmitter has output swing of 510 mV with −6 dB post-tap equalization, and it consumes 15.1 mW under 1.2 V power supply.