PURPOSE: To provide a digital control type PLL device and also to provide a pulse generator and a frequency variable oscillator which are suitable to construct the PLL device.
CONSTITUTION: A PLL device divides a data obtained by coding the cycle of a reference signal by a number to be multiplied to input the result of the division to an oscillation circuit 16 and produces an output signal Po by multiplying the frequency of the reference signal through the circuit 16. Then the PLL device is provided with a pulse generator 20 which generates the pulse signals in the frequency corresponding to the value (lower N bits) less than the decimal point of the result of division. When the signal is outputted, the data obtained by adding 1 to the value (higher M bits) more than the decimal point of the result of division is inputted to the circuit 16. Thus the cycle means value of the signal Po corresponds to the result of division. The generator 20 consists of a counter 26 of signals Po, a register 22 which latches lower N bits and a selector string 24 consisting of N pieces of selectors S1-S3.
WATANABE TAKAMOTO
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