Filter amplifier

Claim 1

A FOUR TERMINAL FILTER AMPLIFIER COMPRISING: (A) A PAIR OF INPUT TERMINALS; (B) FIRST AND SECOND NETWORKS CONNECTED IN SERIES TO SAID INPUT TERMINALS, AT LEAST ONE OF THE NETWORKS INCLUDING A TRANSISTOR, (1) SAID FIRST NETWORK COMPRISING FIRST IMPEDANCE AND RESISTANCE MEANS CONNECTED IN A FIRST PARALLEL CIRCUIT, (2) SAID SECOND NETWORK COMPRISING SECOND IMPEDANCE AND RESISTANCE MEANS CONNECTED IN A SECOND PARALLEL CIRCUIT, (3) SAID PARALLEL CIRCUIT BEING CONNECTED TO EACH OTHER IN SERIES ACROSS SAID INPUT TERMINALS, (4) THE IMPEDANCES AND RESISTANCE OF SAID FIRST AND SECOND IMPEDANCE AND RESISTANCE MEANS SATISFYING THE RELATION IN THE PASS-BAND OF SAID FILTER AMPLIFIER THAT THE PRODUCE OF RESISTANCES IS SUBSTANTIALLY EQUAL TO THE PRODUCT OF IMPEDANCES, AND IN THE ATTENUATION BAND OF SIAD FILTER AMPLIFIER THAT THE IMPEDANCES OF THE IMPEDANCES MEANS ARE SUBSTANTIALLY EQUAL, (5) AT LEAST ONE OF SAID RESISTANCE MEANS COMPRISING THE INPUT RESISTANCE APPEARING BETWEEN THE BASE AND EMITTER ELECTRODES OF SAID TRANSSITOR, (C) MEANS FOR DERIVING AN OUTPUT VOLTAVE SUBSTANTIALLY PROPORTIONAL TO THE DIFFERENCE BETWEEN THE VOLTAGE WHICH APPEARS ACROSS SAID FIRST AND SECOND RESISTANCE MEANS RESPECTIVELY, (1) AT LEAST ONE OF SAID VOLTAGES INCLUDING THE OUTPUT VOLTAGE APPEARING ACROSS THE EMITTER AND COLLECTOR ELECTRODES OF SAID TRANSISTOR; (D) AND A PAIR OF OUTPUT TERMINALS CONNECTED TO SAID DERIVING MEANS.