Optimal Optical Receivers in Nanoscale CMOS: A Tutorial

Abstract

The integration of optical receivers in nanoscale CMOS technologies is challenging due to less intrinsic gain and more noise compared to SiGe BiCMOS technologies. Recent research revealed that low-noise, high-gain, and lowpower CMOS optical receivers can be designed by limiting the bandwidth of the front-end followed by equalization techniques that benefit from good switching characteristics offered by CMOS technologies. In this tutorial brief, the operation of decision-feedback equalization, feed-forward equalization, and continuous-time linear equalization is reviewed in the context of high baud-rate 2-PAM and 4-PAM modulation. Recent advances and techniques in 4-PAM optical receivers are reviewed and compared in terms of speed, sensitivity, bandwidth, and efficiency.