Temp. stabilising circuit for UHF power amplifier stage - uses DC negative feedback without reducing AC gain

摘要

The working point temperature stabilising circuit, for a UHF power amplifier stage in common emitter configuration, has a resistor (6) connected between the positive dc supply and the transistor's inductive collector load (3). The resistor is shunted by a limiting diode (7) and decoupled by a capacitor (5). A reverse-biassed zenor diode (8) is connected in series with a resistor (9) between the diode-load junction and the transistor's base circuit. The advantage lies in using dc negative feedback to provide temp. stabilisation without reducing the ac gain.