Over 200-GHz-Bandwidth InP DHBT Baseband Amplifier ICs and Ultrabroadband Modules With 1-/0.8-mm Coaxial Connectors

Wideband baseband amplifier ICs were designed and fabricated in in-house 250-nm indium phosphide (InP) double-heterojunction bipolar transistor (DHBT) technology for the emerging needs of over 100–150-GHz bandwidth applications. We propose combining an RC degeneration (RCD) circuit and a cascode stage peaking (CSP) circuit to achieve a broadband peaking characteristic and a wide bandwidth. The fabricated amplifier IC achieved a bandwidth of over 200 GHz. To use the amplifier ICs in practical applications, we packaged the amplifier ICs as amplifier modules with 1-mm coaxial connectors as well as 0.8-mm coaxial connectors. The amplifier ICs were mounted onto quartz glass-based module substrates by flip-chip bonding to avoid large reflection and loss. Ground blocks (GBs) were used at the connection part between the module substrates and the coaxial connectors to suppress radiation loss. The fabricated amplifier module with 1-mm coaxial connectors achieved a 7.3-dB gain with a bandwidth over 130 GHz. The fabricated amplifier module with 0.8-mm coaxial connectors achieved an 8.3-dB gain with a 165-GHz bandwidth, which is the widest ever reported thus far.