A Broadband InP Track-and-Hold Amplifier Using Emitter Capacitive/Resistive Degeneration

In this letter, we present a 24-GSa/s, 20-GHz wideband track-and-hold amplifier (THA) based on indium phosphide (InP) double-heterojunction bipolar transistor (DHBT) technology for high-speed sampling systems. In the proposed approach, the output pole of the input stage is canceled by the zero produced by the emitter capacitive/resistive degeneration, and the bandwidth is thereby extended without voltage drop. The compensation technique for Vbe modulation in the output stage is introduced to reduce distortion. The monolithic microwave integrated circuit (MMIC) prototype occupies only 0.69 mm
²
, and the experimental results show that it has a 0.112- fT bandwidth from dc to 22.3 GHz, which is wider than any ratio reported compact THA solutions using the InP technology. In addition, a spurious-free dynamic range (SFDR) of better than 42 dB and total harmonic distortion (THD) of less than -25 dBc are demonstrated at a 24-GSa/s sampling rate. The THA consumes only 374 mW, which is among the lowest dc power dissipation reported for the InP technology.