Temperature compensated frequency generating circuit

Abstract

The frequency of an integrated oscillator is held constant by using temperature compensation to compensate for the component variations due to temperature variations. A voltage controlled oscillator, which has temperature dependent components, is compensated with a temperature dependent control voltage. The frequency of many kinds of oscillators such as a relaxation oscillators and ring oscillators can be held constant when the operating current is held constant. The operating current is often derived from a current source, which is a voltage to current converter with a current equal to the ratio of a control voltage to a resistance. Since semiconductor resistance has a positive temperature coefficient is used to obtain a temperature invariant current source. The positive temperature coefficient is obtained with the difference junction voltage of two forward-biased pn junction voltages. The magnitude can be controlled by junction areas of the two junctions. The magnitude can also be amplified.

Dependencies are inferred from the claim text.