| 摘要 |
PURPOSE:To contrive the improvement of the signal characteristic and to reduce the system cost by providing a circuit amplifying and frequency-dividing an input signal from a signal input terminal and a switching circuit selecting the changeover of an output signal of the circuit or other signal. CONSTITUTION:In a frequency divider integrated circuit 10, the frequency division operating mode frequency-dividing a 1st input signal through a route of 1st amplifier 2 frequency divider 3 switching circuit 7 2nd amplifier 8 and amplifying/outputting the result, and the amplification operation mode amplifying (without frequency dividing) a 2nd input signal through the route of 3rd amplifier 5 switching circuit 7 2nd amplifier 8 and then outputting the result are selected by a control input. Thus, the circuit is used as it is as a prescaler 20 for a PLL used at a broad frequency band. For example, when the prescaler 20 is in the frequency division mode, PLL for a high frequency signal is formed and when the prescaler 20 is in said amplification mode, the PLL for a low frequency signal is formed. |
