TEMPERATURE COMPENSATION CRYSTAL OSCILLATOR AND ITS CHARACTERISTIC OPTIMIZING METHOD

摘要

PROBLEM TO BE SOLVED: To easily adjust the compensation characteristic and to attain accurate temperature compensation by writing a coefficient and a constant for a function for temperature compensation to a P-ROM depending on the temperature characteristic of an oscillation circuit. ;SOLUTION: A cubic function generating circuit 4 generates with a coefficient and a constant of a term of each order of a cubic function received from a P-ROM 6 or a RAM 7 with respect to ambient temperature detected by a temperature sensor 5 and gives it to a varactor element 3 as a control signal. The P-ROM 6 is a so-called one-time P-ROM in which data are once written by laser trimming or power trimming or the like and the data having been written once in the P-ROM 6 are maintained even when power supply is interrupted. The RAM 7 is provided in parallel with the P-ROM 6 and used selectively and the RAM 7 is a circuit extracting an output resulting from demodulating serial data and latched by a latch circuit.;COPYRIGHT: (C)1997,JPO