A Dual-Polarization Silicon-Photonic Coherent Receiver Front-End Supporting 528 Gb/s/Wavelength
Abdelrahman H. Ahmed, Leonardo Vera, Lorenzo Iotti, Ruichang Shi, Sudip Shekhar, Alexander Rylyakov
Abstract
Supporting advanced modulation schemes such as 16 quadrature-amplitude modulation (QAM) in a high-speed transimpedance amplifier (TIA) requires minimizing noise and total harmonic distortion (THD) across gain settings and frequency. Accordingly, our automatically reconfigurable TIA reduces base resistor noise, gain peaking, phase margin (PM) degradation, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{T}$ </tex-math></inline-formula> degradation, operating on a single sense voltage and eliminating the need for multiple control loops. A collaborative offset and dc current cancellation technique is introduced to reduce offset-induced nonlinearity, while protecting the receiver (RX) against current overdrive. A prototype of the RX is fabricated on 130-nm SiGe BiCMOS process and demonstrates a maximum gain of 75.5 dB <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> with 35.5 dB of dynamic range, 42-GHz bandwidth (BW), and a maximum gain averaged input-referred noise (IRN) of 18.5 pA/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sqrt {\text {Hz}}$ </tex-math></inline-formula> . The silicon-photonic transceiver assembly incorporating four such RXs achieves 25-dB required optical signal to noise ratio (ROSNR) for received optical power between–22 and 1 dBm at 50 Gbaud, and aggregate data rate of 528 Gb/s/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda$ </tex-math></inline-formula> at 66 Gbaud and 25-dB ROSNR.