Method and apparatus to improve frequency stability of an integrated circuit oscillator

Abstract

An apparatus providing a simple low cost integrated circuit oscillator with improved frequency stability over a range of selected frequencies by reducing the impact of process and temperature variations on a base current of bipolar transistor of the integrated circuit oscillator. A circuit includes a capacitor coupled to be alternatingly charged and discharged by first and second current sources. A first voltage follower circuit including a first bipolar transistor having a base is coupled to the capacitor. The first bipolar transistor is biased such that a voltage at an emitter of the first bipolar transistor follows a voltage on the capacitor. A current mirror having first and second current paths is included. The first current path is coupled to the base of the first bipolar transistor. The first current path provides substantially all of a base current received by the base of the first bipolar transistor. A second voltage follower circuit including a second bipolar transistor having a base coupled to the second current path is included. The second current path provides substantially all of a base current received by the base of the second bipolar transistor.

Dependencies are inferred from the claim text.