EP0423941A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Variable frequency signal generator
Assignee: Marconi Instruments Ltd
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Filing: 1990-09-19
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Granted: —
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Expires: 2010-09-19
Abstract
Abstract A variable frequency signal generator includes a phase locked loop having a variable frequency oscillator (1) which has a control port to which a frequency determining signal is applied, the output of the oscillator being fed via a frequency divider (6) to a phase sensitive detector (7) where it is compared with a reference frequency signal, the result of said comparison being arranged to generate a comparison signal which is fed to a loop filter (9) which is coupled to said control port; and the signal generator including means for applying a frequency control signal thereto comprising a first path being arranged to adjust the division ratio of the frequency divider (6), and a second path including means for combining said frequency control signal and said comparison signal to produce said frequency determining signal; and calibration means (11-14) for adjusting the relative characteristics of said first and second paths to compensate for effects arising from tuning sensitivity dependence on frequency of said variable frequency generator (1).
Inventors
- 👤 David Paul Owen
- 👤 John Norman Wells
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 06:35
CPC Classifications
H; H03; H03C; H03C3/00; H03C3/02; H03C3/09; H03C3/0908; H03C3/0991; H03B; H03B23/00; H03C3/0916; H03C3/0925; H03C3/0933; H03C3/0941; H03C3/095; H03B2200/00; H03B2200/006; H03B2200/0092; H03C2200/00; H03C2200/0004; H03C2200/0029; H03C2200/0037; H03C2200/005; H03C2200/0079; H03C3/06
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
159 words
A variable frequency signal generator includes a phase locked loop having a variable frequency oscillator which has a control port to which a frequency determining signal is applied, the output of the oscillator being fed via a frequency divider to a phase sensitive detector where it is compared with a reference frequency signal, the result of said comparison being arranged to generate a comparison signal which is fed to a loop filter which is coupled to said control port; and the signal generator including means for applying a frequency control signal thereto comprising a first path being arranged to adjust the division ratio of the frequency divider, and a second path including means for combining said frequency control signal and said comparison signal to produce said frequency determining signal; and calibration means for adjusting the relative characteristics of said first and second paths to compensate for effects arising from tuning sensitivity dependence on frequency of said variable frequency generator.
Claim 2
Dependent Claim
159 words
A variable frequency signal generator includes a phase locked loop having a variable frequency oscillator which has a control port to which a frequency determining signal is applied, the output of the oscillator being fed via a frequency divider to a phase sensitive detector where it is compared with a reference frequency signal, the result of said comparison being arranged to generate a comparison signal which is fed to a loop filter which is coupled to said control port; and the signal generator including means for applying a frequency control signal thereto comprising a first path being arranged to adjust the division ratio of the frequency divider, and a second path including means for combining said frequency control signal and said comparison signal to produce said frequency determining signal; and calibration means for adjusting the relative characteristics of said first and second paths to compensate for effects arising from tuning sensitivity dependence on frequency of said variable frequency generator.
Claim 3
Dependent Claim
82 words
A generator as claimed in Claim 1 wherein said calibration means includes adjustable gain means located in said first and/or second path, a detection means coupled to a control means for adjusting the gain of said adjustable gain means, and wherein said detection means is operative in a calibration mode of operation to compare said comparison signal with said control signal whereby said control means adjusts the adjustable gain means to bring the output of the detection means to a predetermined level.
Claim 4
Dependent Claim
31 words
A generator as claimed in Claim 2 wherein said detection means is a coherent detector which provides an output representative of both amplitude and phase of the comparison and control signals.
Claim 5
Dependent Claim
27 words
A generator as claimed in Claim 2 wherein said control means includes processor means and a memory, and said gain means comprises a digitally gain controlled amplifier.
Claim 6
Dependent Claim
80 words
A generator as claimed in Claim 4 wherein said generator includes means for providing a carrier frequency instruction to said frequency divider and also to said control means, so that in the calibration mode, the gain of the adjustable gain means is adjusted for each of a plurality of frequency values, the gain values being stored in said memory whereby in normal operation the gain of said adjustable gain means is charged to the respective value for the operating frequency.
Claim 7
Dependent Claim
25 words
A generator as claimed in any preceding claim, wherein said means for applying a frequency control signal is arranged to apply a frequency modulation signal.
Claim 8
Dependent Claim
24 words
A generator as in any of Claims 1 to 6 where the means for generating a frequency control signal is a direct digital synthesiser.
Claim 9
Dependent Claim
30 words
A generator as claimed in Claim 7 wherein said direct digital synthesiser comprising a phase accumulator coupled to a look-up table for applying a waveform signal to said frequency divider.
Claim 10
Dependent Claim
56 words
A generator as in Claim 7 and Claim 5 where the direct digital synthesiser uses a look up table in the second modulation path, the contents of which have been modified according to the results obtained by the calibration means in such a way as to compensate for the non linear voltage/frequency characteristics of the oscillator.
Claim 11
Dependent Claim
40 words
A generator as claimed in any of Claims 1 to 6 wherein said means for applying a frequency control signal comprises frequency instruction means for applying a frequency instruction signal which hops between values of a preselected set of values.
Claim 12
Dependent Claim
39 words
A generator as claimed in Claim 10 when dependent on Claim 5 wherein said memory of said control means provides a look-up table on said second path arranged to provide a modified frequency instruction signal in said second path.
References Cited (Backward Citations)
No citation records indexed.
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