Northern Telecom Limited

Stephen G Roy

Samuel Alfred Tiller

In an amplifier circuit, bias feedback to an amplifying transistor is provided by interconnecting the DC bias voltage applied to the transistor output and the transistor input with a feedback circuit consisting of a switching transistor and bias resistors. Bias current and stable operation is provided by this design. In a particular embodiment two common emitter amplifying transistors are connected to a common output and each has a separate bias feedback circuit including a respective switching transistor. A single DC control input connected to the inputs of both switching transistors can be used to switch between the two amplifying transistors depending on the value of the control voltage thereby amplifying either an input signal of the first amplifying transistor or an input signal of the second amplifying transistor.

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Ottawa, Canada

Stephen G Roy