| 摘要 |
PROBLEM TO BE SOLVED: To switch the frequency at high speed when a frequency channel number for specifying the output frequency is transmitted externally, in an oscillation device including a voltage controlled oscillator and a PLL circuit.SOLUTION: As a frequency divider 3 in a PLL circuit, a pulse swallow counter by a dual modulus prescaler is used. Frequency division ratio N of the frequency divider 3 is represented by N=BP+A (N, B, A, P are integers), and when a frequency channel number for specifying the output frequency is transmitted externally, calculations of Z=A(1)+(channel number-1)*Nstep, A=Z/P (remainder), B=B(1)+Z/P (quotient) are performed, for the values B(1) and A(1) when the frequency channel number is (1), and then A, B are determined, before changing the frequency division ratio and switching the output frequency. |
