A 1–271-GHz Ultra-Broadband Amplifier Based on Synthesis of Multiple Amplifier Topologies

This paper presents an ultra-broadband amplifier architecture that extends the bandwidth of conventional distributed amplifiers beyond their fundamental limitations. The proposed approach combines a baseband (BB) distributed amplifier with a radio frequency (RF) band amplifier, forming a “BB-RF amplifier” topology. To ensure smooth transition between the two bands, band joint adjusters (BJAs) based on transmission lines are introduced to mitigate phase mismatch at the band joint frequency. The amplifier was fabricated in 250 nm InP double heterojunction bipolar transistor (DHBT) technology with a maximum oscillation frequency (fmax) of 480 GHz. Measurements show a gain of 11 dB at 1 GHz and a bandwidth of 270 GHz, ranging from 1 GHz to 271 GHz. The fmax-normalized bandwidth is 0.56, marking the highest value ever reported.