80-GBd 3-Vppdiff PAM-4 InP DHBT linear driver

This article reports the design, fabrication and characterization of a new differential linear driver, fabricated in the III-V Lab 0.7um emitter width Indium phosphide (InP) double heterojunction bipolar transistor (DHBT) technology. Large-signal electrical characterization shows 80-GBd symbol-rate four-level pulse amplitude (PAM-4) modulation conjugated with a driver output swing of 3-Vppdiff and a 0.74-W power consumption. The single-ended output power is 9-dBm, at 1-dB of gain compression, at 1 GHz. S-parameter measurements of the standalone linear driver exhibit an 8.4-dB low frequency gain (14.4 differential), a 106-GHz -3-dB bandwidth and a 6.2-dB peaking gain at 59.4-GHz, while the input/output reflection coefficients remain better to -10 dB up to 92/100 GHz.