| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit configuration which independently controls a coefficient of an approximate cubic function so as to easily adjust cubic function control voltage of a temperature compensation type crystal oscillator (TCXO), and has a configuration simplified and compacted. SOLUTION: The approximate cubic function generation circuit 100 is provided with: a first differential amplifier 103 in which a linear function signal is inputted to one input terminal and a first constant level signal is inputted to the other input terminal; a second differential amplifier 104 in which the linear function signal is inputted to one input terminal and a second constant level signal is inputted to the other input terminal; and synthesizing circuits 114 and 115 for synthesizing voltage outputs of the first and second differential amplifiers 103 and 104, and outputting an approximate cubic function component. In addition, one differential amplifier constitutes a linear component function, and is provided with a circuit for dividing an output of the differential amplifier into N systems and adding the output to an offset signal, and a synthetic circuit for synthesizing outputs of the N systems. COPYRIGHT: (C)2008,JPO&INPIT
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