Design of PAM4 modulation circuit with 2-tap pre-emphasis for millimeter-wave application

Abstract

Millimeter-wave (mmWave) technology has been employed in many applications due to abundant bandwidth resources and high interference immunity such as telecommunication, automotive radars, and imaging. In this paper, a mmWave transmitter link incorporating PAM4 modulation, resonant tunneling diode (RTD) based oscillator, power amplifier and antenna was proposed. To achieve good linearity and alleviate inter-symbol interference (ISI) caused by channel loss simultaneously, a PAM4 modulation circuit utilizing voltage mode driver and 2-tap pre-emphasis was designed and optimized in TSMC 28 nm CMOS process. The simulation results show that our PAM4 modulation circuit operates properly at 40Gb/s with a differential output swing of up to 800 mVpp under a supply voltage of 0.9 V. The overall power consumption is about 51.3 mW, corresponding to an energy efficiency of 1.28 pJ/bit.