A 19-dB Peaking at 72-GHz and 4.1-Vppd Output Swing SiGe BiCMOS Linear Driver with Dynamic Cascode Output Buffer

As symbol rate increases over 100 GBd in digital coherent optical communication system, high-frequency loss compensation becomes a critical issue. This paper presents a 4-ch lumped linear driver IC with 19-dB peaking at 72 GHz, variable by over 6 dB, which is favorable for high-frequency loss compensation. Low frequency gain is 25 dB at maximum and variable by over 18 dB, which is beneficial for compensating amplitude decrease caused by de-emphasis. P1dB is over 4-Vppd from 1 to 50 GHz. A novel open collector output buffer with a dynamic cascode and series inductors realized such large peaking and excellent linearity. Designed by 55-nm SiGe BiCMOS technology, the driver IC integrates a control circuit with serial peripheral interface (SPI) compliant with optical internetworking forum (OIF) standard and the power dissipation is 0.54 W/ch including the control circuit. A coherent driver modulator (CDM) assembled with this driver IC shows 9.7 % error vector magnitude (EVM) with 128-GBd single polarization 16 quadrature amplitude modulation (QAM) operation under back-to-back configuration.