Dual feedback amplifier

Claim 1

A broadband amplifier circuit comprising: a high gain noninverting amplifier element having an input circuit path and an output circuit path, input means for coupling said input circuit path to a signal source having an impedance Z S , output means for coupling said output circuit path to a load having an impedance Z L , first frequency dependent feedback means having a voltage transfer function a connected between said circuit paths for coupling in series with said input circuit path a voltage substantially equal to a times the output voltage of said amplifier element, second frequency dependent feedback means having a current transfer function b connected between said circuit paths for coupling in shunt with said input circuit path, a current substantially equal to b times the current in said output circuit path, the parameters of said feedback means being chosen to satisfy the expressions ##EQU23## in order to generate a desired frequency dependent amplifier circuit gain characteristic G, an amplifier circuit input impedance substantially equal to Z S , the conjugate of said source impedance Z S , and an amplifier circuit output impedance substantially equal to Z L , the conjugate of said load impedance Z L , 1/|ab| being the reciprocal of the magnitude of the product of said transfer functions.