Variable gain amplifiers

Claim 1

IN A VARIABLE GAIN AMPLIFYING CIRCUIT, IN COMBINATION WITH A SIGNAL SOURCE, AN AMPLIFYING STAGE WHICH INCLUDES A FIRST ELECTRON DISCHARGE DEVICE HAVING AT LEAST AN ANODE, A CATHODE AND A CONTROL ELECTRODE, MEANS FOR APPLYING THE SIGNAL SOURCE THERETO BETWEEN THE CATHODE AND CONTROL ELECTRODE, MEANS FOR APPLYING THE OUTPUT THEREFROM BETWEEN THE CATHODE AND ANODE TO AN OUTPUT CIRCUIT, MEANS FOR AMPLIFYING A PART OF THE SIGNAL SOURCE, FIRST RECTIFYING MEANS CONNECTED TO THE OUTPUT OF SAID AMPLIFYING MEANS, A FIRST TIMING NETWORK CONNECTED TO SAID RECTIFYING MEANS RESPONSIVE TO RECTIFIED SIGNALS THEREFROM, CONTROL MEANS CONNECTED BETWEEN SAID TIMING NETWORK AND THE ELECTRON DISCHARGE DEVICE TO CONTINUOUSLY CONTROL THE GAIN OF SAID DEVICE IN RESPONSE TO THE SIGNAL DEVELOPED IN SAID TIMING NETWORK, FIRST BIASING MEANS TO RENDER SAID RECTIFYING MEANS NON-CONDUCTIVE AND TO DEVELOP A PREDETERMINED CONSTANT SIGNAL IN SAID TIMING NETWORK WHEN THE AMPLIFIED PART OF THE SIGNAL SOURCE IS BELOW A FIRST PREDETERMINED LEVEL, WHEREBY SAID DEVICE PRODUCES SUBSTANTIALLY LINEAR GAIN BELOW MAXIMUM OPERATING GAIN, SAID BIASING MEANS RENDERING SAID RECTIFYING MEANS CONDUCTIVE WHEN THE AMPLIFIED PART OF THE SIGNAL SOURCE EXCEEDS THE FIRST PREDETERMINED LEVEL TO DEVELOP INCREASING SIGNAL IN SAID TIMING NETWORK WITH INCREASING AMPLITUDES OF THE SIGNAL SOURCE, WHEREBY SAID DEVICE PRODUCES INCREASING GAIN, AND LIMITING MEANS CONNECTED ACROSS THE JUNCTION OF SAID RECTIFYING MEANS AND SAID TIMING NETWORK LIMITING THE RESPONSE OF SAID TIMING NETWORK TO RECTIFIED SIGNALS OF A SECOND PREDETERMINED LEVEL OF GREATER AMPLITUDE THAN THE FIRST PREDETERMINED LEVEL, WHEREBY SAID DEVICE PRODUCES SUBSTANTIALLY LINEAR GAIN AT SUBSTANTIALLY MAXIMUM OPERATING GAIN, A SECOND RECTIFYING MEANS CONNECTED TO PART OF THE AMPLIFIED SIGNAL SOURCE APPEARING AT THE OUTPUT CIRCUIT, A SECOND TIMING NETWORK CONNECTED BETWEEN THE SECOND RECTIFYING MEANS AND THE FIRST TIMING NETWORK, THE SECOND TIMING NETWORK BEING RESPONSIVE TO RECTIFIED SIGNALS FROM THE SECOND RECTIFYING MEANS, THE CONTROL MEANS BEING CONNECTED BETWEEN THE JUNCTION OF SAID TIMING NETWORKS AND THE ELECTRON DISCHARGE DEVICE TO FURTHER CONTINUOUSLY CONTROL THE GAIN OF SAID DEVICE IN RESPONSE TO THE SIGNAL DEVELOPED IN THE SECOND TIMING NETWORK, SECOND BIASING MEANS TO RENDER THE SECOND RECTIFYING MEANS NON-CONDUCTIVE WHEN SAID PART OF THE AMPLIFIED SIGNAL SOURCE APPEARING AT THE OUTPUT CIRCUIT IS BELOW A THIRD PREDETERMINED LEVEL OF GREATER AMPLITUDE THAN THE SECOND PREDETERMINED LEVEL, THE SECOND BIASING MEANS RENDERING THE SECOND RECTIFYING MEANS CONDUCTIVE WHEN SAID PART OF THE AMPLIFIED SIGNAL SOURCE APPEARING AT THE OUTPUT CIRCUIT EXCEEDS THE THIRD PREDETERMINED LEVEL TO DEVELOP DECREASING SIGNAL IN THE SECOND TIMING NETWORK WITH INCREASING AMPLITUDES OF THE SIGNAL SOURCE, WHEREBY SAID DEVICE PRODUCES DECREASING GAIN.