Frequency synthesizer
First Claim
1. A frequency synthesizer comprising:
- voltage-controlled oscillating means;
frequency-dividing means for dividing an output from said voltage-controlled oscillating means with a frequency-dividing ratio of 1/N and with a frequency-dividing ratio of 1/(N+1) for providing at least two frequency divided output signals, where N is an arbitrary integer;
a signal source for outputting a reference frequency signal;
phase comparing means for phase-comparing said frequency divided output signals having said frequency-dividing ratios of 1/N and 1(N+1) from said frequency-dividing means and said reference frequency signal supplied thereto from said signal source;
adding means for adding a first signal from said phase comparing means resulting from phase-comparing said reference frequency signal and said signal frequency-divided by said frequency-dividing ratio of 1/N and a second signal from said phase comparing means resulting from phase-comparing said reference frequency signal and said signal frequency-divided by said frequency-dividing ratio of 1/(N+1);
converting means for converting an output from said adding means and supplying a DC output for controlling said voltage-controlled oscillating means; and
control means receiving one of said at least two frequency divided output signals for controlling said frequency-dividing ratios of said frequency-dividing means, wherein said control means changes said frequency-dividing ratio of said frequency-dividing means to 1/N or 1/(N+1) cyclically and on an alternating basis.
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Accused Products
Abstract
A frequency synthesizer includes a voltage-controlled oscillator, frequency dividing circuits, a signal source, phase comparing circuits, an adding circuit, a converting circuit and a control circuit. The frequency dividing circuits divide an output supplied thereto from the voltage-controlled oscillator with frequency-dividing ratios of 1/N and 1/(N+1) where N is an arbitrary integer. The signal source outputs a reference frequency signal. The phase comparing circuits phase-compare a signal divided by N supplied thereto from one frequency dividing circuit and a signal divided by (N+1) supplied thereto from another frequency dividing circuit and the reference frequency signal from the signal source. The adding circuit adds a signal which results from phase-comparing the reference frequency signal output from the phase comparing circuit and the signal divided by N and a signal which results from phase-comparing the reference frequency signal output from the phase comparing circuit and the signal divided by (N+1). The converting circuit converts an output from the adding circuit to a DC signal and supplies the same to the voltage-controlled oscillator. The control circuit controls frequency-dividing ratios of the frequency dividing circuits. The control circuit cyclically changes the frequency-dividing ratios of the frequency dividing circuits to 1/N or 1/(N+1).
117 Citations
6 Claims
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1. A frequency synthesizer comprising:
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voltage-controlled oscillating means; frequency-dividing means for dividing an output from said voltage-controlled oscillating means with a frequency-dividing ratio of 1/N and with a frequency-dividing ratio of 1/(N+1) for providing at least two frequency divided output signals, where N is an arbitrary integer; a signal source for outputting a reference frequency signal; phase comparing means for phase-comparing said frequency divided output signals having said frequency-dividing ratios of 1/N and 1(N+1) from said frequency-dividing means and said reference frequency signal supplied thereto from said signal source; adding means for adding a first signal from said phase comparing means resulting from phase-comparing said reference frequency signal and said signal frequency-divided by said frequency-dividing ratio of 1/N and a second signal from said phase comparing means resulting from phase-comparing said reference frequency signal and said signal frequency-divided by said frequency-dividing ratio of 1/(N+1); converting means for converting an output from said adding means and supplying a DC output for controlling said voltage-controlled oscillating means; and control means receiving one of said at least two frequency divided output signals for controlling said frequency-dividing ratios of said frequency-dividing means, wherein said control means changes said frequency-dividing ratio of said frequency-dividing means to 1/N or 1/(N+1) cyclically and on an alternating basis. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification