Matsushita Electric Industrial Co., Ltd.

Shuji Shibuya

Hisato Takeuchi

Takaharu Saeki

Yuichi Tateyama

Junichi Matsuura

Makoto Eguchi

A temperature compensating crystal oscillation device includes a constant voltage circuit (,) for outputting a predetermined voltage independent of the ambient temperature, a temperature sensor circuit (,) for outputting a voltage in proportion to the ambient temperature, and a control circuit (,) for receiving the constant voltage output from the constant voltage circuit (,) and the voltage output in proportion to the temperature from the temperature sensor circuit (,) and for generating a control voltage (Vc) used for compensating a temperature characteristic of a quartz oscillator in the entire range of the ambient temperature through polygonal lines approximation of a negative cubic curve by using continuous lines. Furthermore, the crystal oscillation device includes a VCXO (,) whose oscillation frequency is controlled to be a predetermined value by the control voltage (Vc), and a ROM/RAM circuit (,) for storing temperature compensating parameters used for compensation of a temperature characteristic of the control voltage (Vc) for optimizing the oscillation frequency of the VCXO (,).

Function generator, crystal oscillation device and method of adjusting crystal oscillation device

In order to realize highly accurate temperature compensation of a crystal oscillation frequency, a current in proportion to the cube of a difference between an ambient temperature T.sub.a and a reference temperature T.sub.0 is generated. For this purpose, provided are a first series circuit of two diodes; a second series circuit of three diodes; a third series circuit of two diodes; a fourth series circuit of three diodes; a current source for allowing a constant current to flow into the first series circuit; a current source for allowing a constant current to flow from the third series circuit; a current source for allowing a current in proportion to T.sub.a -T.sub.0 to flow into the second series circuit when T.sub.a .gtoreq.T.sub.0 and allowing a current in proportion to .vertline.T.sub.a -T.sub.0 .vertline. to flow from the fourth series circuit when T.sub.a &lt;T.sub.0 ; an NPN transistor and a PNP transistor whose collectors are connected with an output terminal; and two operational amplifiers for applying a voltage between the anode terminals of the first and second series circuits between the base and the emitter of the NPN transistor and for applying a voltage between the cathode terminals of the third and fourth series circuits between the base and the emitter of the PNP transistor, respectively.

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Kanagawa, Japan

Shuji Shibuya