11.4 FET SAMPLING GATES

FET sampling gates can again be of two types: (i) a series gate and (ii) a shunt gate. The FET is simply used as a switch. In a series gate the FET switch is used as series element. Whereas in a shunt gate the FET switch is used as a shunt element. The advantage with FET and Op-amp sampling gates is that the input resistance is large and hence, the problem of loading is avoided.

11.4.1 FET Series Gates

The Fig. 11.23(a) shows a sampling gate where the switch is used as a series element. The practical switch can be an n-channel FET. FET series gate is essentially a voltage switch. [see Fig. 11.23(b)]

The input Vs, control signal VC and the output waveforms are shown in Fig. 11.23(c). The input Vs is a triangular wave, the ...

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