GB1338276A - Synchronous modulator-demodulators - Google Patents

Abstract

1338276 Transistor amplifying circuits; pulse modulation circuits TRANCHANT ELECTRONIQUE SA 19 April 1971 [24 June 1970] 27073/71 Headings H3T and H4L In a chopper type amplifier in which the earths of the input and output circuits are isolated from each other, the input V e is applied to transformer primary T31 over the seriesconnected emitter-collector paths of transistors Q31-Q34 which are driven conductive by means of a square waveform applied to the bases over transformer secondaries L31,L33 and series resistors R31-R34. The output from transformer secondary T32 is demodulated by means of a synchronously gated demodulator comprising the series-connected emitter-collector paths of transistors Q35-Q38 which are driven by means of square waves applied to the bases over transformer secondaries L35, L37 and series resistors R35-R38. The output is smoothed by means of a capacitor C40 shunting the load R40. Distortion may be corrected by non-linear means such as the impedance variation of a semiconductor element. The Specification also refers to a known type of modulator comprising four transistors giving full-wave modulation (Fig. 1, not shown) and to a second known type of modulator with transistors connected in series (Fig. 2, not shown).