| 摘要 |
PROBLEM TO BE SOLVED: To overcome the problem such that the use of a RC low-pass filter to generate sinusoidal wave output from a standard signal tends to cause variation between the phases of the sine wave and the standard signal depending on the temperature. SOLUTION: A capacitor C is charged with the time constant determined by the product of a resistance R6 and a capacitance C when only a control signal D3 is ON, and with the time constant of parallel resistance of R6 and R7 and capacitance C when an additional control signal D4 is ON. Similarly, the capacitor C is charged with the time constant determined by the product of resistance R4 and capacitance C when only a control signal D1 is ON, and with the time constant parallel resistance of R4 and R5 and capacitance C when an additional control signal D2 is ON. A control signal generating means 20 controls each of control signals D1, D2, D3, and D4 so that the output of a buffer means 5 OUT is a sine wave, and this provides a accurate sine wave without the effect of temperature and therefore without the delay of phase. |
