Patent ID: 6034566
Filing Date: 2000-03-07
Classification: H03F,H03H

Abstract:
A tuning amplifier comprising:an adding circuit for adding an input signal and a feedback signal;two phase shifting circuits of a full band pass type including a differential amplifier wherein an output is returned to the input side; anda voltage dividing circuit interposed into one part of the feedback loop formed by connecting in cascade each of said two phase shifting circuits;wherein the added signal from said adding circuit is applied to the front stage phase shifting circuit of said two cascade connected phase shifting circuits, the output signal from the subsequent stage phase shifting circuit is applied to said adding circuit as said feedback signal,and wherein portions of an input signal to the front stage phase shifting circuit are provided to an inverting input and portions of the input signal to the front stage phase shifting circuit are provided to a non-inverting input of the differential amplifier front stage phase shifting circuit, and an AC signal input to said voltage dividing circuit is output as a tuned signal.