EP0215651A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
A circuit including a DC-FM phase locked loop
Assignee: Wavetek GmbH
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Filing: 1986-09-12
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Granted: —
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Expires: 2006-09-12
Abstract
Abstract A DC-FM phase locked loop is provided for use in transmitters for measuring and control purposes, wherein the modulation signal controls, via an A/D converter (11), the output frequency (14) of a frequency synthesizer (13), this output frequency being used as the reference for the phase comparator (6). This permits modulation with extremely low frequencies or DC without the necessity to interrupt the loop.
Inventors
- 👤 Johann Schutz
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 01:03
CPC Classifications
H; H03; H03C; H03C3/00; H03C3/02; H03C3/09; H03C3/0908; H03C3/0966; H03C3/0941; H03C3/0958
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
164 words
A circuit including a DC-EM phase locked loop, the circuit comprising a variable frequency oscillator having a control input for a modulation signal, a frequency divider connected between the output of said oscillator feeding one input of a phase comparator, a second input of said phase comparator being connected to receive a reference frequency. and the output of said phase comparator being connected, via a filter, to a frequency control input of said oscillator. wherein a quartz-stabilized but frequency-variable frequency generator is provided for the generation of said reference frequency, and wherein said modulation signal is fed via a low pass filter to the input of an analog-to-digital converter for conversion to corresponding digital signals, which are fed to control inputs of said frequency generator so as to cause the output reference frequency produced by said generator to fluctuate, in response to low frequency and DC components of said modulation signal. by substantially the same amount as the output frequency of said frequency divider.
Claim 2
Dependent Claim
164 words
A circuit including a DC-EM phase locked loop, the circuit comprising a variable frequency oscillator having a control input for a modulation signal, a frequency divider connected between the output of said oscillator feeding one input of a phase comparator, a second input of said phase comparator being connected to receive a reference frequency. and the output of said phase comparator being connected, via a filter, to a frequency control input of said oscillator. wherein a quartz-stabilized but frequency-variable frequency generator is provided for the generation of said reference frequency, and wherein said modulation signal is fed via a low pass filter to the input of an analog-to-digital converter for conversion to corresponding digital signals, which are fed to control inputs of said frequency generator so as to cause the output reference frequency produced by said generator to fluctuate, in response to low frequency and DC components of said modulation signal. by substantially the same amount as the output frequency of said frequency divider.
Claim 3
Dependent Claim
20 words
A circuit as claimed in claim 1, wherein said frequency generator is arranged to change frequency substantially without phase jumps.
Claim 4
Dependent Claim
30 words
A circuit as claimed in claim 1 or claim 2, wherein the frequency generator output signal is directly fed to said phase comparator as the reference frequency for the latter.
Claim 5
Dependent Claim
51 words
A circuit as claimed in claim 1 or claim 2, wherein the frequency generator output is mixed with a substantially higher quartz-stabilized frequency and the frequency mix is fed to the input of a frequency divider having a division ratio such that said reference frequency will be produced at its output.
Claim 6
Dependent Claim
22 words
A circuit as claimed in claim 4, wherein said quartz-stabilized frequency is fed to said frequency generator as a frequency basis thereof.
References Cited (Backward Citations)
US3622913A
Cited
US4481489A
Cited
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