Design of 20-Gb/s four-level pulse amplitude modulation VCSEL driver in 90-nm CMOS technology

摘要

Using 4-level pulse amplitude modulation (PAM-4) technique, the transmission data bit rate of the system or circuit can be doubled at the same bandwidth, compared to non-return zero (NRZ) binary modulation. In this paper, a PAM-4 vertical cavity surface emitting laser (VCSEL) diode driver circuit was designed in 90 nm CMOS technology. Through our circuit, two 10-Gb/s non-return zero (NRZ) input signals can be combined as a 20-Gb/s (10-GBaud/s) PAM-4 output current signal to drive a VCSEL diode. In our laser diode driver (LDD) circuit, the total modulation current is about 6.2mA, the power consumption is 34.1mW, and the chip size is 0.5×0.62 mm2. The VCSEL driver can be suitable to use in the transmitter module of short range optical fiber communications.