120 GBd 2.8 Vpp,diff low-power differential driver for InP Mach-Zehnder modulator using 55 nm SiGe HBTs

We present a 120 GBd 2.8 Vpp,diff driver for InP Mach-Zehnder modulator using 55 nm SiGe HBTs. The output impedance of the driver has a differential 2 × 25 Ω, matched to the optical modulator. The measured 3 dB bandwidth exceeds 67 GHz, and output P1dB is about 16.7 dBm at 1 GHz. The variable gain using the Gilbert-cell is implemented, and 2.1 dB gain variation is measured. The total harmonic distortion is 2.5 % at 1 GHz. The power consumption is 960 mW. The eye openings up to 120 GBd are characterized exploiting the impedance conversion IC, which is de-embedded afterwards. The post-processing of the de-embedding results in the rail-to-rail voltage output of 2.8 Vpp,diff.