FREQUENCY DISCRIMINATOR Russian patent published in 1994 - IPC

FIELD: radio engineering. SUBSTANCE: improved noise immunity of frequency discriminator is achieved by insertion of supplementary bipolar transistor which collector is connected to collectors of first and second bipolar transistors and load resistor, by insertion of resistive voltage divider shifting base of third transistor and by insertion of two diodes linking base of this transistor with bases of first and second bipolar transistors. Increased sensitivity is obtained by insertion of forward-biased diode in parallel to base-emitter junction of third bipolar transistor. In addition to mentioned components there are inserted four transistors controlled by input signal and shunting base-emitter junctions of first and second bipolar transistors. Thanks to them passing of carrier to output of frequency discriminator is attenuated additionally. EFFECT: improved noise immunity, increased sensitivity of frequency discriminator. 5 dwg