| 摘要 |
PURPOSE:To obtain a stable oscillation output in which the variable width of a frequency is wide at a variable mode and an oscillating frequency is not changed at a fixed mode by minimizing the resistance value of the terminal resistance of a crystal filter when the oscillating frequency is fixed and setting largely the resistance value when the oscillating frequency is made variable. CONSTITUTION:When the resistance value of a terminal resistance is minimized, the changing ratio of an oscillating frequency to the change of a phase comes to be made smaller. When the resistance value of the terminal resistance is enlarged, the changing ratio of the oscillating frequency to the change of a phase comes to be made larger. At the fixed mode, the low level is supplied to a terminal 23. Consequently, the electric current will not flow at a resistance 16 and a resistance 34 comes to be a terminal resistance. At the variable mode, a high level is supplied to the terminal 23 and the serial connection of the resistance 16 and the resistance 34 comes to be the terminal resistance. Thus, the resistance value of the terminal resistance is made into a small value at the fixed mode and the resistance value of the terminal resistance is made into the large value at the variable mode. Thus, the stable oscillating output is obtained at the fixed mode and the frequency variable width can be widened at the variable mode.
|
