A SWITCHED-CURRENT SAMPLE-AND-HOLD CIRCUIT

A switched-current sample-and-hold circuit is reported. The circuit wa s fabricated in a 0.8-mu m BiCMOS process, Measurements indicate a sam pling frequency of 57 MHz with 60 dB signal-to-noise-plus-distortion-r atio and suggest that operation at sampling frequencies beyond 80 MHz is feasible. Comparisons of this circuit with other switched-current s ample-and-hold circuits are given to highlight the strengths and weakn esses of the circuit. The feasibility of the sample-and-hold circuit a s an under-sampler intended for the Canadian CT2Plus personal communic ation system is also presented.