| 摘要 |
PURPOSE:To switch the oscillation frequency in a short period by adding a simple circuit. CONSTITUTION:Plural low-pass filters 6A, 6B supplying control voltage to a phase locked loop voltage control oscillator 7 are prepared. The voltage control oscillator 7 is immediately made to oscillate other frequency by holding the control voltage by the low-pass filters 6A, 6B according to the time constant by frequency when these are switched by oscillation frequency in a selector circuit 8, by providing an initilization setting circuit 9 and by making the phase of the output of the variable frequency division of a programmable counter 3 immediately after the low-pass filters 6A, 6B are switched and the phase of the reference signal in a reference oscillator 2 even. |
