Apparatus for eliminating on-off transitional gain variations in class ab, b and c active element amplifiers

Claim 1

A high fidelity audio amplifier comprising: input means to the amplifier adapted to receive an input signal to be amplified; a pair of cooperating active amplifying devices having their respective control inputs operatively connected to said input means and connected to drive a common output in response to an input signal in a mode wherein one active amplifying device is driven more conductive in response to changes of input signal from a zero level while the other active amplifying device is driven less conductive, and vice versa; bias means for maintaining both of said active amplifying devices in a conductive state when no input signal is provided to the amplifier; circuit means for providing a current to each of said active amplifying devices; first and second diode means respectively associated with said active amplifying devices for controlling the current to said active amplifying devices for maintaining said active amplifying devices in a conductive state for input signal values which, when combined with the bias from said bias means would render one or the other of said active amplifying devices nonconductive without said circuit means; and output means operatively connected to said active amplifying devices for cooperatively combining the respective output signals from said active amplifying devices to provide an amplified output signal from the amplifier.