A ${4} \times \text{112-Gb}/\mathrm{s}$, 3.51-pJ/Bit Monolithically Integrated Silicon-Photonic Transceiver for High-Density Co-Packaged Optics

A <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4 \times 112-\text{Gb} / \mathrm{s}$</tex> Si-photonic (SiPh) transceiver (O-TRX) for co-packaged optics (CPO) is presented in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$45-\text{nm}$</tex> SOI CMOS. By monolithically integrating electronic circuits and photonic devices on one chip, high bandwidth density and high power efficiency is achieved. A high-swing open-drain driver is codesigned with the traveling-wave Mach-Zehnder Modulator (MZM) to reach high speed at low power. A compact-size inverter-based trans-impedance amplifier (TIA) is cooptimized with the photodetector (PD). Multi-node inductive peaking is employed to extend bandwidth while maintaining a linear phase delay. The O-TRX loopback is demonstrated at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$112-\text{Gb} / \mathrm{s} /$</tex> lane under PAM-4 modulation. Measurement results show the OTX achieves <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$224-\text{Gb} / \mathrm{s} / \text{mm}$</tex> bandwidth density with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2.36-\text{pJ} /$</tex> bit power efficiency, while the ORX attains <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$299 \text{Gb} / \mathrm{s} / \text{mm}$</tex> density with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.15-\text{pJ} /$</tex> bit efficiency.