Automatic gain control circuit for if-amplifiers of a large bandwidth

Claim 1

A WIDE BAND AUTOMATIC GAIN CONTROLLED IF-AMPLIFIER COMPRISING AT LEAST FIRST AND SECOND STAGES OF AMPLIFICATION HAVING AUTOMATIC GAIN CONTROL, AT LEAST A THIRD STAGE OF AMPLIFICATION HAVING NO AUTOMATIC GAIN CONTROL, EACH OF SAID STAGES COMPRISING AN ELECTRONIC DEVICE HAVING AT LEAST ELECTRON-EMISSION AND CONTROL ELECTRODES, MEANS FOR PROVIDING SAID AUTOMATIC GAIN CONTROL BY APPLYING A VARIABLE DIRECT CURRENT BIAS TO THE CONTROL ELECTRODES OF SAID FIRST AND SECOND STAGES, MEANS FOR APPLYING A FIXED DIRECT CURRENT BIAS TO THE CONTROL ELECTRODE OF SAID THIRD STAGE, AN INPUT TERMINAL FOR RECEIVING WIDE BAND IF INPUT SIGNALS COUPLED TO THE CONTROL ELECTRODE OF SAID FIRST STAGE, AN OUTPUT TERMINAL CONNECTED TO THE OUTPUT OF SAID THIRD STAGE, COUPLING MEANS FOR CONNECTING SAID FIRST, SECOND, AND THIRD STAGES IN CASCADE, QUADRIPOLE CIRCUIT MEANS INCLUDED IN THE COUPLING BETWEEN SAID FIRST AND SECOND STAGES FOR PROVIDING A CONSTANT D.C. RESISTANCE OVER SAID WIDE BAND, MEANS COMPRISING A VARIABLE NETWORK CONNECTED IN SHUNT WITH SAID QUADRIPOLE MEANS FOR PROVIDING PURELY OHMIC DAMPING RESISTANCE, SAID VARIABLE NETWORK INCLUDING A FIRST RESISTOR CONNECTED IN SERIES WITH THE ELECTRON-EMISSION ELECTRODE OF SAID FIRST STAGE, A SECOND RESISTOR CONNECTED IN SERIES WITH THE ELECTRON-EMISSION ELECTRODE OF SAID THIRD STAGE, SAID FIRST AND SECOND RESISTORS CARRYING CURRENT TO THE ASSOCIATED ELECTRON-EMISSION ELECTRODES, AND SAID NETWORK COMPRISONG COMPENSATING MEANS CONNECTED FROM SAID FIRST AND SECOND RESISTORS TO THE COUPLING MEANS BETWEEN SAID FIRST AND SECOND STAGES FOR VARYING SAID OHMIC RESISTANCE OF SAID NETWORK TO CONTROL THE ATTENUATION OF SAID FIRST AND SECOND STAGES RESPONSIVE TO A DIFFERENCE IN THE CURRENT TRAVERSING SAID FIRST AND SECOND RESISTORS THEREBY MAINTAINING CONSTANT TRANSMISSION PROPERTIES OF SAID AMPLIFIER AND PROVIDING A SUBSTANTIALLY CONSTANT OUTPUT SIGNAL AMPLITUDE AT SAID OUTPUT TERMINAL THROUGHOUT A WIDE RANGE INPUT SIGNAL AMPLITUDE.