A 50Gb/s DAC-Based Multicarrier Polar Transmitter in 22nm FinFET

Abstract

A DAC-based polar transmitter (TX) for wireline applications efficiently implements jitter-robust multicarrier signaling with arbitrary modulation formats. 50Gb/s total data rate is supported by three parallel 5GS/s output drivers operating with baseband PAM-4 and mid-band (MB) and highband (HB) 16-state complex modulation on 5 and 10GHz orthogonal carriers. DAC amplitude resolution is 7b plus 2b predistortion for all drivers, while the polar MB and HB drivers also have 7b phase resolution. The TX DSP implements 8-tap FIR filtering on all bands. Fabricated in 22nm FinFET, the TX has 1.2$\mathrm{V}_{\mathrm{p}\mathrm{p}\mathrm{d}}$ swing and achieves 50Gb/sBER<$10^{-4}$ with both QAM-16 and APSK-4+12 modulations at 1. 68pJ/b.