GB1290255A - - Google Patents

Abstract

1290255 Transistor amplifying circuits DECCA Ltd 19 April 1971 [16 April 1970] 17000/70 Heading H3T A radio frequency power amplifier comprises a number of parallel-connected transistors 24, 25 driven in cascode from a further transistor 26. Transistor 26 is driven from an emitterfollower 22 and negative feedback is applied between output and input by means of a current transformer 27, the secondary of which feeds into a resistive network 21, 28, 29 in the input. The transistors 22, 26 may be replaced by a pair in Darlington connection and the secondary of transformer 27 be shunted with a resistor and connected in series in the input signal path (Fig. 3, not shown): two such circuits may be arranged in push-pull (Fig. 4, not shown). In another embodiment output transistor 65, Fig. 5, is driven from the emitter circuit of a transistor 61 of complementary type, which itself is driven from a transistor 60 of the first type, the primary winding 62 of feedback current transformer being connected in the collector circuit of transistor 61: two such circuits may be arranged in push-pull (Fig. 6, not shown).