| 摘要 |
A programmable integer and fractional frequency divider is provided. The programmable divider divides a frequency of an input signal by a first divisor to generate an output signal, and comprises a programmable integer frequency divider and a fractional number switch. The programmable integer frequency divider divides the frequency of the input signal by a second divisor to generate the output signal, wherein the second divisor is first or second integers depending on a divisor switching signal. The fractional number switch calculates a pulse count of the output signal, and generates the divisor switching signal to switch from the first to the second integer when the pulse count of the output signal equals to a predetermined pulse count determined by a fractional part of the first divisor, and receives a fractional divisor control signal to change the predetermined pulse count, thereby changing the fractional part of the first divisor.
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