GB1276741A - Improvements in or relating to electronic switches - Google Patents

Abstract

1276741 Field effect transistor switches; pulse modulation circuits SOLARTRON ELECTRONIC GROUP Ltd 30 April 1970 [30 April 1969 8 Oct 1969] 22114/69 Headings H3T and H4L Switching spikes in a field effect transistor switch are removed by feeding an anti-phased switching wave to a second control electrode of the transistor or to the gate of a further transistor having an output electrode connected to an output electrode of the switch transistor. In Fig. 2 the compensating transistor 35 is connected through a capacitor 36 in parallel with a chopper transistor 15, the drain-gate capacitance serving to feed an anti-phase chopping wave to the output of the chopper. Accurate balance may be obtained by a stiff wire 37 positioned between the transistors and bent to differentially adjust the capacitances. In Fig. 3 (not shown), capacitor 36 is omitted and the compensating transistor is switched between two non-conducting states. In Fig. 4 (not shown) the chopping wave is fed in antiphase to two gates. Fig. 1 (not shown) illustrates a chopper type amplifier with a known anti-phase despiking arrangement which chopper and the phase sensitive detector may be replaced by a chopper circuit in accordance with the invention.