Patent ID: 6489845
Filing Date: 2002-12-03
Classification: H03F,H03G,H03K

Abstract:
A multiplexing amplifier circuit which receives a plurality of input signals selected by a plurality of select control signals, the multiplexing amplifier circuit comprising:an amplifier which provides an output signal indicative of the input signal at a positive input and a negative input; a selection circuit corresponding to each input signal having a longtail pair of first and second transistors wherein the first transistor receives the input signal and drives the negative input of the amplifier and the second transistor receives the feed back output signal and drives the positive input of the amplifier; a pair of diodes connected to each transistor for steering the current through the transistor; wherein each select signal biases the corresponding diodes to thereby cause its corresponding longtail transistor pair to provide the corresponding input signal to the amplifier inputs.