| 摘要 |
PROBLEM TO BE SOLVED: To provide a temperature compensated crystal oscillator with an AFC function in which an optimal dynamic range can be designed. SOLUTION: The temperature compensated crystal oscillator is comprised of a crystal oscillator 120 comprising crystal connecting terminals (Xtal1, Xtal2), a compensation voltage generating circuit 100 for generating a temperature compensation voltage in response to frequency/temperature characteristics of the crystal oscillator 120, a first voltage variable capacitance element 111 and a second voltage variable capacitance element 112 which are inserted into an oscillation closed loop of the crystal oscillator 120. If the dynamic range of an AFC control voltage from an automatic frequency control circuit 130 is greater than that of the compensation voltage from the compensation voltage generating circuit 100, the compensation voltage from the compensation voltage generating circuit 100 is applied to the first voltage variable capacitance element 111, and the AFC control voltage from the automatic frequency control circuit 130 is applied to the second voltage variable capacitance element 112. COPYRIGHT: (C)2005,JPO&NCIPI
|
