A 16/32 Gb/s Dual-Mode NRZ/PAM4 Voltage-Mode Transmitter With 2-Tap FFE

Abstract

This paper describes a voltage-mode transmitter that supports both non-return-to-zero (NRZ) and four-level pulse amplitude modulation (PAM4) signal transmission. A 2-tap feed-forward equalizer (FFE) is implemented with PAM4 equalization logic consisting of three stages of logic gates and two separated voltage-mode drivers for multi-level generation. Equalization is performed in both the NRZ and PAM4 signal transmission modes. A prototype chip is fabricated using a 28-nm CMOS process. When transmitting 500-mVp-p signals using the proposed transmitter, 41.13 mW power is consumed from a 1-V power supply during the 32-Gb/s PAM4 transmission.

Keywords

• Driver circuits
• equalization
• feed-forward equalizer (FFE)
• non-return-to-zero (NRZ)
• pulse amplitude modulation (PAM4)
• transmitters