RADIO RECEIVER UNIT Russian patent published in 1997 - IPC

FIELD: radio engineering. SUBSTANCE: radio receiver unit has line channel incorporating input circuit and intermediate-frequency adjustable amplifier; it is made in the form of series-connected variable-gain component and fixed-gain component, amplitude detector, and low-frequency amplifier, as well as series connected automatic gain control (AGC) circuit amplifier and AGC filter inserted between additional output of amplitude detector and control input of variable-gain component made in the form of broad-band two- stage directly coupled amplifier whose first stage is, essentially, amplifier built around thyristor connected into common-emitter circuit with resistor in emitter circuit of transistor; second stage is amplifier built around thyristor using common-emitter circuit and provided with series negative DC feedback circuit and parallel negative voltage feedback circuit, shunting component connected in parallel with line channel frequency changer and made in the form of two parallel circuits one of which has series-connected first diode connected in parallel with first resistor, and second resistor; second circuit has second diode; first and second diodes are connected in opposition; points of connection of second resistor and diode is connected to input of broad-band two-stage amplifier through first isolating capacitor; receiver unit also has L-shaped voltage divider connected to output of broad-band two-stage amplifier through second isolating capacitor whose longitudinal arm has third resistor and transverse one, parallel, connected circuits of which one has third diode and other, series-connected fourth resistor and fourth diode; third and fourth diodes are connected in opposition; voltage divider is made in the form of series-connected fifth resistor and sixth resistor connected in parallel with capacitor; divider tap formed by point of connection of fifth and sixth resistors is connected to other lead of resistor in emitter circuit of first-stage transistor of broad-band two-stage amplifier; point of connection of first diode and resistor, other lead of fifth resistor, and point of connection of fourth resistor and diode function as control input of variable-gain component. EFFECT: improved design of receiver possessing linear control characteristic. 2 dwg