A "One-Pin" LC Oscillator Circuit with a New Type of Amplitude Control

A variable-frequency LC oscillator, designed for use in an integrated AM radio receiver, is presented. A constant amplitude of its output voltage is, despite large Q variations, obtained by using a new type of momentary amplitude control which needs no integration capacitor and prevents severe deterioration of phase-noise characteristics. The oscillator needs only one pin for connection of its resonance circuit; all other pins are common to other circuits in the receiver.