Patent ID: 7633350

Claim:
A function generation circuit, which performs temperature compensation for a quartz oscillation apparatus, comprising: a first analog signal generation circuit, for generating and outputting a predetermined analog signal that is not affected by an ambient temperature; a second analog signal generation circuit, for generating and outputting an analog signal that is affected by the ambient temperature and that approximates a first order function; a third order approximation function generation circuit, for receiving the analog signals from the first analog signal generation circuit and the second analog signal generation circuit, and for generating and outputting m control signals (m is an integer of three or greater) corresponding to m contiguous temperature domains that are obtained by dividing a range, available for the ambient temperature, extending from a low temperature side to a high temperature side; a first order function generation circuit, for receiving the analog signal from the second analog signal generation circuit and generating a first order function control signal that is affected by the ambient temperature; a zero-th order function generation circuit, for receiving the analog signal generation circuit from the first analog signal generation circuit and generating a zero-th order function control signal that is not affected by the ambient temperature; a fourth order and fifth order approximation function generation circuit, for employing a g-th control signal (g is an integer of one or greater and m or smaller) and a h-th control signal (h is an integer, other than g, of one or greater and m or smaller), both of which are output by the third order approximation function generation circuit in consonance with a g-th temperature domain and an h-th temperature domain, respectively, and generating control signals that approximate a fourth order function and a fifth order function; and an adder, for synthesizing the signal output by the third order approximation function generation circuit, the analog signal output by the first order function generation circuit, the zero-th order function control signal output by the zero-th order function generation circuit, and the control signals output by the fourth order and the fifth order approximation function generation circuit, and outputting the resultant signal.