Frequency converter for outputting a stable frequency by feedback via a phase locked loop
First Claim
1. A frequency converter, comprising:
- local oscillator means for generating a local oscillation frequency signal;
a mixer for mixing said local oscillation frequency signal and a feedback frequency signal to generate a mixed frequency signal;
a first filter for outputting a first filtered frequency signal by filtering said mixed frequency signal;
a phase comparator for generating a voltage signal corresponding to a phase difference between an input frequency to said frequency convertor and said first filtered frequency signal output from said first filter;
a second filter for converting said voltage signal output by said phase comparator to a direct-current (DC) voltage having any noise component eliminated by said second filter; and
a voltage controlled oscillator receiving said DC voltage as a first control voltage for generating a stable output frequency signal, said stable output frequency signal being provided as said feedback frequency signal to said mixer.
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Accused Products
Abstract
A frequency converter capable of providing a highly stable frequency by frequency feedback using a phase locked loop circuit. The frequency converter includes a local oscillator; a frequency converter for mixing an output of the local oscillator and a feedback frequency therefrom to generate a mixed frequency; a first filter for filtering the mixed frequency; a phase comparator for generating a voltage signal corresponding to a phase difference in between an input frequency to the frequency convertor and the output frequency of the first filter; a second filter for converting the voltage signal of the phase comparator to a constant polarity voltage and eliminating any noise component of the converted voltage signal; and a voltage controlled oscillator receiving the output of the second filter as a control voltage so as to provide a stable output frequency by generating the feedback frequency responsive to the control voltage.
146 Citations
15 Claims
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1. A frequency converter, comprising:
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local oscillator means for generating a local oscillation frequency signal; a mixer for mixing said local oscillation frequency signal and a feedback frequency signal to generate a mixed frequency signal; a first filter for outputting a first filtered frequency signal by filtering said mixed frequency signal; a phase comparator for generating a voltage signal corresponding to a phase difference between an input frequency to said frequency convertor and said first filtered frequency signal output from said first filter; a second filter for converting said voltage signal output by said phase comparator to a direct-current (DC) voltage having any noise component eliminated by said second filter; and a voltage controlled oscillator receiving said DC voltage as a first control voltage for generating a stable output frequency signal, said stable output frequency signal being provided as said feedback frequency signal to said mixer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A frequency converter, comprising:
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a local oscillator for generating a local oscillation frequency signal; a first amplifier for providing a local frequency signal by amplifying said local oscillation frequency signal to a first predetermined level; a second amplifier for outputting an amplified frequency signal by amplifying said local oscillation frequency signal; a divider for dividing said amplified frequency signal output from said second amplifier; a phase locked loop circuit for generating a first direct-current (DC) voltage by comparing an output of said divider to an input reference clock frequency signal and filtering a resultant thereof, said first DC voltage being applied as a first control voltage for controlling said local oscillator; a mixer for mixing said local frequency signal and a feedback frequency signal to generate a mixed frequency signal; a first filter for outputting a first filtered frequency signal by filtering said mixed frequency signal; a phase comparator for generating a voltage signal corresponding to a phase difference between an input frequency to said frequency convertor and said first filtered frequency signal output from said first filter; a second filter for converting said voltage signal output by said phase comparator to a second DC voltage having any noise component eliminated by said second filter; and a voltage controlled oscillator receiving said second DC voltage as a second control voltage for generating a stable output frequency signal, said stable output frequency signal being provided as said feedback frequency signal to said mixer. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification