Transistor radio signal receiver with means for reducing distortion in the rf amplifier
First Claim
4. IN A SIGNAL RECEIVER OF THE TYPE COMPRISING A RADIO FREQUENCY AMPLIFIER STAGE INCLUDING A TRANSISTOR HAVING BASE, EMITTER AND COLLECTOR ELECTRODES, AND HAVING A SIGNAL INPUT CIRCUIT CONNECTED BETWEEN SAID BASE AND EMITTER ELECTRODES, AN INTERMEDIATE FREQUENCY AMPLIFIER STAGE COMPRISING A TRANSISTOR INCLUDING BASE, EMITTER AND COLLECTOR ELECTRODES MEANS PROVIDING AN AUTOMATIC GAIN CONTROL CIRCUIT FOR DEVELOPING A CONTROL VOLTAGE THE MAGNITUDE OF WHICH IS A FUNCTION OF THE RECEIVED SIGNAL LEVEL, AND MEANS FOR APPLYING SAID CONTROL VOLTAGE TO A GAIN CONTROLLING ELECTRODE OF SAID INTERMEDIATE-FREQUENCY AMPLIFIER STAGE TRANSISTOR TO REDUCE THE GAIN THEREOF AS SIGNAL LEVEL INCREASES, THE COMBINATION COMPRISING, A DIRECT CURRENT LOAD IMPEDANCE ELEMENT CONNECTED IN THE EMITTER-COLLECTOR CURRENT PATH OF SAID INTERMEDIATE FREQUENCY AMPLIFIER STATE TRANSISTOR TO DEVELOP A DIRECT VOLTAGE CORRESPONDING TO SAID CONTROL VOLTAGE, VOLTAGE RESPONSIVE NONLINEAR IMPEDANCE MEANS CONNECTED ACROSS THE RADIO FREQUENCY AMPLIFIER STAGE INPUT CIRCUIT AND TO SAID LOAD IMPEDANCE ELEMENT FOR APPLYING SAID DIRECT VOLTAGE TO A GAIN CONTROLLING ELECTRODE OF SAID RADIO FREQUENCY AMPLIFIER STAGE TRANSISTOR SO THAT THE BASE-EMITTER CURRENT AND THE GAIN OF SAID RADIO FREQUENCY AMPLIFIER IS REDUCED AS SIGNAL LEVEL INCREASES, AND MEANS FOR PROVIDING A GREATER INCREMENTAL CHANGE IN COLLECTOR CURRENT OF SAID RADIO FREQUENCY AMPLIFIER THAN THE INCREMENTAL CHANGE IN COLLECTOR CURRENT OF SAID INTERMEDIATE FREQUENCY AMPLIFIER FOR A GIVEN CHANGE OF SIGNAL LEVEL SO THAT FOR CHANGES OF SIGNAL LEVEL IN A PREDETERMINED RANGE OF SIGNAL SUBSTANTIALLY ONLY THE GAIN OF SAID RADIO FREQUENCY AMPLIFIER IS CHANGED.
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9 Citations
4 Claims
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4. IN A SIGNAL RECEIVER OF THE TYPE COMPRISING A RADIO FREQUENCY AMPLIFIER STAGE INCLUDING A TRANSISTOR HAVING BASE, EMITTER AND COLLECTOR ELECTRODES, AND HAVING A SIGNAL INPUT CIRCUIT CONNECTED BETWEEN SAID BASE AND EMITTER ELECTRODES, AN INTERMEDIATE FREQUENCY AMPLIFIER STAGE COMPRISING A TRANSISTOR INCLUDING BASE, EMITTER AND COLLECTOR ELECTRODES MEANS PROVIDING AN AUTOMATIC GAIN CONTROL CIRCUIT FOR DEVELOPING A CONTROL VOLTAGE THE MAGNITUDE OF WHICH IS A FUNCTION OF THE RECEIVED SIGNAL LEVEL, AND MEANS FOR APPLYING SAID CONTROL VOLTAGE TO A GAIN CONTROLLING ELECTRODE OF SAID INTERMEDIATE-FREQUENCY AMPLIFIER STAGE TRANSISTOR TO REDUCE THE GAIN THEREOF AS SIGNAL LEVEL INCREASES, THE COMBINATION COMPRISING, A DIRECT CURRENT LOAD IMPEDANCE ELEMENT CONNECTED IN THE EMITTER-COLLECTOR CURRENT PATH OF SAID INTERMEDIATE FREQUENCY AMPLIFIER STATE TRANSISTOR TO DEVELOP A DIRECT VOLTAGE CORRESPONDING TO SAID CONTROL VOLTAGE, VOLTAGE RESPONSIVE NONLINEAR IMPEDANCE MEANS CONNECTED ACROSS THE RADIO FREQUENCY AMPLIFIER STAGE INPUT CIRCUIT AND TO SAID LOAD IMPEDANCE ELEMENT FOR APPLYING SAID DIRECT VOLTAGE TO A GAIN CONTROLLING ELECTRODE OF SAID RADIO FREQUENCY AMPLIFIER STAGE TRANSISTOR SO THAT THE BASE-EMITTER CURRENT AND THE GAIN OF SAID RADIO FREQUENCY AMPLIFIER IS REDUCED AS SIGNAL LEVEL INCREASES, AND MEANS FOR PROVIDING A GREATER INCREMENTAL CHANGE IN COLLECTOR CURRENT OF SAID RADIO FREQUENCY AMPLIFIER THAN THE INCREMENTAL CHANGE IN COLLECTOR CURRENT OF SAID INTERMEDIATE FREQUENCY AMPLIFIER FOR A GIVEN CHANGE OF SIGNAL LEVEL SO THAT FOR CHANGES OF SIGNAL LEVEL IN A PREDETERMINED RANGE OF SIGNAL SUBSTANTIALLY ONLY THE GAIN OF SAID RADIO FREQUENCY AMPLIFIER IS CHANGED.
Specification
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Current AssigneeJohn B. Schultz
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Original AssigneeJohn B. Schultz
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InventorsSchultz, John B.
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Application NumberUS04/184,049Time in Patent Office1,191 DaysField of SearchUS Class Current455/243.1CPC Class CodesH03G 3/3068 Circuits generating control...
