一种50 Gb/s PAM4外调制激光器驱动电路

50 Gb/s PAM4 external modulation laser driver circuit

激光器驱动电路是光通信系统中发射端的重要部件,为了适应高速电/光转换的需求,基于28 nm互补金属氧化物半导体(CMOS)工艺,设计了一种外调制激光器(EML)驱动电路,整个驱动电路采用了5级级联的架构,分别包括可变增益放大器(VGA)、两级连续时间线性均衡器(CTLE)、预放大器和输出级,驱动电路内部采用了新型的互补放大和共源共栅结构,驱动电路的输入为50 Gb/s的4阶脉冲振幅调制(PAM4)信号。仿真结果表明:该驱动电路小信号带宽为27 GHz;在12.5 GHz、0.16~0.312 VPP正弦输入下的输出摆幅为1 VPP时,总谐波失真(THD)大小为2.21%,电压增益范围为13.98~20.24 dB,总功耗为340 mW。

The laser driving circuit is an important part of the transmitter in the optical communication system.In order to meet the needs of high-speed electric/optical conversion,an externally modulated laser(EML)driving circuit is designed based on the 28 nmcomplementary metal oxide semiconductor(CMOS)process.The whole driving circuit adopts a five-stage cascade architecture,including variable gain amplifier(VGA)and two-stage continuous time linear equalizer(CTLE),preamplifier and output stage.The driving circuit adopts a new complementary amplification and cascode structure,the input of the drive circuit is a 50 Gb/s fourth-order pulse amplitude modulation(PAM4)signal.The simulation results show that the small signal bandwidth of the driving circuit is 27 GHz.When the output swing is 1 VPP at 12.5 GHz and 0.22 VPP sinusoidal input,the total harmonic distortion(THD)is 2.21%.The voltage gain range is 13.98~20.24 dB,and the total power consumption is 340 mW.