GB928977A - Improvements in or relating to push-pull transistor amplifiers for audio frequencies - Google Patents

Abstract

928,977. Transistor amplifying circuits. MULLARD Ltd. March 29, 1962, No. 12109/62. Class 40 (6). The output circuit of a push-pull transistor amplifier comprises a pair of symmetrical limbs each limb including the series arrangement of a first transistor, a first primary winding of an output transformer and a second transistor having connected in its collector circuit a second primary winding of the transformer, the first transistor having a higher # cut-off frequency than the second transistor. The Figure shows one of the symmetrical limbs of a class AB pushpull amplifier and comprises a driver transistor T feeding the base of a first output transistor T1 having a #-cut-off-frequency of the order of 20 kc/s. and its emitter connected in series with a primary winding P1 of output transformer Q. The collector of transistor T1 is connected to the emitter of common base connected transistor T2 having a #-cut-off frequency of the order of 5 kc/s. and a second primary winding P2 of transformer Q connected in series with its collector electrode. The primary winding P1 may be connected between the collector of transistor T1 and the emitter of transistor T2. The transistors may be PNP, NPN types or a combination of the two types.