Sample and hold circuitry in bipolar transistor technology using a

Abstract

A sample-and-hold circuit is formed in bipolar transistor technology with the aid of clocked and complementary-clocked bipolar transistors in combination with a holding capacitor whose output terminal, in going from sample to hold phases of the clock, undergoes change in voltage .DELTA.V equal to the input voltage samples Vin applied to its input terminal during the sample phases (electrical bootstrapping operation). In particular, an input terminal of the holding capacitor is connected to a clocked input voltage device that ensures that, during the sample phases, the input voltage applied to the input terminal of the capacitor represents the input voltage being sampled, and that during the hold phases of the clock, the input terminal of the capacitor is electrically clamped. An output terminal of the holding capacitor is connected to one of the clocked transistors and to an auxiliary bipolar transistor whose base terminal is controlled by a complementary-clocked voltage-dropping device. This complementary-clocked voltage-dropping device sets the output terminal of the capacitor to a fixed voltage during the sample phases and is disconnected from this output terminal during the hold phases, whereby during the hold phases the output terminal of the holding capacitor is electrically floating and the voltage thereat represents the input voltage during the immediately preceding sample phase.