A 2.4 Vpp, 60-Gb/s, mm-Wave DAC-Based CMOS Driver with Adjustable Amplitude and Peaking Frequency

A 60-Gb/s CMOS driver employing mm-wave DACs to achieve broadband waveshape control and pre-emphasis at different peaking frequencies is presented. It features a modified distributed amplifier (DA) architecture that achieves low-voltage and high-speed summation of both low-pass and reactively-coupled bandpass signal paths along an output transmission line. Using binary-weighted MOSFET gate fingers in Gilbert-cell based DACs, the circuit can supply variable output swing up to 1.2V peak-to-peak per side in a 50Ω load and independent digital pre-emphasis control at 25 GHz, 35 GHz and 45 GHz, respectively. S-parameter measurements of the entire retimed transmitter show 60dB of differential gain, while the standalone DA exhibits approximately 10 dB of peaking control in each of the three frequency bands. Input and output return loss is better than - 10 dB up to 60 GHz. The entire circuit, including the transimpedance-limiting-amplifier-retimer, operates from 1.2V and 2V supplies and achieves a throughput efficiency of 12.2 mW/Gb/s.