Abstract: A method provides a temperature controlled frequency source. The method reduces the effects of temperature variations on an operating frequency of the temperature controlled frequency source by temperature compensating the temperature controlled frequency source.

Abstract: Apparatus (1) for generating a control signal for a tunable circuit (3) sensitive to temperature receives an input control signal and predistorts it in a distortion circuit (4), so that the output (5) of the tunable circuit (3) will be substantially corrected for non-linearities in the tunable circuit (3). The distortion circuit (4) includes a linear non-distortion circuit element (9), which may be a linear temperature compensation element, and one or more non-linear distortion circuit elements (12, 13, 14), each of which distort the input control signal according to a different function. The outputs of the distortion circuit elements are passed to variable gain elements (17, 18, 19, 20) to produce weighted components. The weighted linear and non-linear components are then combined in a combination circuit element (8) to provide a predistorted control signal to the tunable circuit (3).