A 20GHz BW 4GSPS Track-Hold Amplifier with Switched Emitter Follower

A Track-Holding Amplifier (THA) was designed using a 0.18μm SiGe BiCMOS process. The circuit employs a switched emitter-follower (SEF) topology, where the inclusion of clock signals in the input buffer stage enables independent control over the base and emitter terminals of the core transistor within the SEF structure. A clock buffer module was incorporated to optimize the rise/fall time of the clock signal. This design achieves an input bandwidth of 20.2 GHz, a spurious-free dynamic range (SFDR) of 62.48 dB, and a sampling rate of 4 GSPS.