METHOD AND APPARATUS FOR FILTERING RADIO FREQUENCY SIGNALS

摘要

A variable frequency active filter circuit for tuning in a specific bandpass frequency is disclosed. The active filter incorporates a controlled oscillator circuit for tuning into a specific frequency range. A frequency input signal controls the active filter bandpass frequency by tuning the oscillator circuit to a desired frequency. The controlled oscillator circuit further includes a gain input. The gain input is set to a value just below where the oscillator circuit would oscillate.