中圖分類號： TN432
文獻標識碼： A
DOI： 10.19358/j.issn.2096-5133.2020.06.010
引用格式： 李喜，林福江. 一種高速大電流的PAM4光發(fā)射機設(shè)計[J].信息技術(shù)與網(wǎng)絡(luò)安全，2020，39(6)：53-57.

Design of a high-speed PAM4 optical transmitter with large current

Abstract： With the continuous improvement of the communication data bit rate, PAM4(four-level pulse amplitude modulation) optical transmitters are more widely used in ultra-high-speed optical fiber communication systems. A PAM4 optical transmitter including NRZ(non-return-to-zero) encoding to RZ(return-to-zero) encoding converter is designed in this paper. Based on current mode logic, it increases the circuit′s working speed and anti-interference ability. The self-biased controllable delay circuit is used to realize the converter from NRZ encoding to RZ encoding, which reduces the dispersion effect of long-link signal transmission. The driver uses a cascade of pre-driver and main driver to increase the driving capability, and achieves common-mode level matching between stages by a series resistor. The circuit design is based on 0.13 μm SOI CMOS process. Simulation results show that the maximum output current is 120 mA, the current pulse width is 125 ps, and the PAM4 eye pattern is open well at an input data rate of 2.5 Gb/s and a typical load of 25 Ω.

Key words : optical-fiber communication；PAM4(four-level pulse amplitude modulation)；optical transmitter；driver circuit