| 摘要 |
PROBLEM TO BE SOLVED: To provide a non-adjustment voltage controlled oscillation circuit in which no affect is given on a temperature characteristic and dispersion even when an externally mounted high precision resistance is built in an IC. SOLUTION: A PLL circuit 18 having a negative feedback loop is made up of a crystal oscillator 11, a phase comparator circuit 12, a low pass filter 13, an adjustment amplifier 14, and a 1st voltage control circuit 15. A signal is subject to voltage/current conversion in the voltage control circuit 15, and a signal with a phase difference of 90 deg. between with a signal of the crystal oscillator 11 is outputted from a current controlled oscillator 17, and an output of the PLL circuit 18 is given to a voltage control circuit 20. The voltage signal is converted into a current by a 2nd V/I conversion circuit consisting of the same components as those in the V/I conversion circuit and a current signal adjusted by a current mirror circuit 22 is converted into a desired oscillation signal by a current controlled oscillator 23. Since the same components are employed for the 1st and 2nd V/I conversion circuits, component dispersion/ temperature characteristic change are compensated and a stable oscillating frequency signal is obtained with inexpensive components. |
