A 10 b 250 MHz BiCMOS track and hold

This BiCMOS track and hold (T&H) circuit is intended for use as the front end of an A/D conversion system. The T&H operates at 250MHz sampling rate and is capable of limiting the harmonic distortion to -62dB for a 70MHz sinewave input. Similar results are obtained with 10MHz input sinewaves and 200MHz sampling frequency. The circuit exhibits hold-mode feedthrough and pedestal errors significantly better than previously-published results. A 12GHz-f/sup T/ O.8/spl mu/m BiCMOS process is used.