Fully bipolar, 120-Msample/s 10-b track-and-hold circuit

Describes the design and experimental results of a fully bipolar track-and-hold (T&H) circuit for use in video applications. A fully differential, open-loop approach has been chosen in order to meet the specifications with respect to track-to-hold step, droop rate, and hold-mode feedthrough. In order to obtain maximum high-frequency performance, p-n-p transistors have been omitted from the design. The T&H circuit has been realized in a 3-GHz f_T bipolar production process with a minimum emitter size of 2*9 mu m². The die size is 0.25 mm², consuming 40 mW from a single 5-V power supply. Ten-bit performance has been measured up to 12-Msample/s full-Nyquist sampling rate. At 200 Msample/2, 8-b performance has been observed over the full-Nyquist band.