Patent US3721904A successfully refreshed from Google Patents.
US3721904A
Expired / Lapsed
US
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Frequency divider
Assignee: US Philips Corp
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Filing: 1971-02-22
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Granted: 1973-03-20
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Expires: 1991-02-22
Abstract
Abstract A signal frequency is divided by a number m n+j by means of an n-divider based, for example, on digital principles. The output pulses of the n-divider switch a monostable multivibrator which blocks an AND-gate during j-pulses of the input signal. The input pulses have to pass the AND-gate so that the frequency is divided by (n+j). If the n-divider consists of various dividing stages, phase transitions occur in the signal between these dividing stages, which can be filtered out or avoided by the introduction of an auxiliary oscillator which is coupled to the first frequency by a phase-sensitive detector. The latter principle is applied in a PAL frequency divider.
Inventors
- 👤 L Verhoeven
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:36
CPC Classifications
H; H03; H03K; H03K23/00; H03K23/64; H03K23/66; H03K23/662; H04; H04N; H04N9/00; H04N9/44; H04N9/45
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
163 words
A device for dividing signal frequencies by a number m, comprising an input terminal for receiving signal frequencies to be divided, an AND-gate having a first input connected to the input terminal of the device, a digital divider having a division ratio of n, n being smaller than m, means for connecting an input of the digital divider to an output of the AND-gate, and delay means comprising a monostable multivibrator having an input connected to the output of the digital divider and having an output connected to an input of the AND-gate for providing an enabling level to the AND-gate wherein pulses from the input terminal pass through the AND-gate to the digital divider and for providing the AND-gate with a blocking pulse having a duration of j periods of the input signal in response to an output of the digital divider, whereby the output frequency of the digital divider, j being a non-zero integer, is divided by a number m n+j.
Claim 2
Independent Claim
163 words
A device for dividing signal frequencies by a number m, comprising an input terminal for receiving signal frequencies to be divided, an AND-gate having a first input connected to the input terminal of the device, a digital divider having a division ratio of n, n being smaller than m, means for connecting an input of the digital divider to an output of the AND-gate, and delay means comprising a monostable multivibrator having an input connected to the output of the digital divider and having an output connected to an input of the AND-gate for providing an enabling level to the AND-gate wherein pulses from the input terminal pass through the AND-gate to the digital divider and for providing the AND-gate with a blocking pulse having a duration of j periods of the input signal in response to an output of the digital divider, whereby the output frequency of the digital divider, j being a non-zero integer, is divided by a number m n+j.
Claim 3
Dependent Claim
27 words
A dividing device as claimed in claim 1, characterized in that the pulse length Tau of the monostable multivibrator is variable for varying the dividing factor j.
Claim 4
Dependent Claim
32 words
A dividing device as claimed in claim 1, characterized in that the phase transitions which occur in the signal which is present between the various stages of the digital divider are filtered.
Claim 5
Dependent Claim
96 words
A dividing device as claimed in claim 1, further comprising an auxiliary oscillator having an auxiliary divider and a phase-sensitive detector, the output frequency of the dividing device being compared in the phase-sensitive detector with the output frequency of the auxiliary divider, the latter frequency being obtained by division from the auxiliary oscillator frequency, the auxiliary oscillator being controllable by the output signal of the phase-sensitive detector so that an accurate phase relation exists between this oscillator and the signal on the input terminal of the first dividing device, and hence also between the various frequencies.
Claim 6
Dependent Claim
26 words
A dividing device as claimed in claim 4, constructed as a PAL frequency divider in which the line and picture frequencies are generated from the PAL-frequency.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-19 | 1976-09-18 | 1977-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-19 | 1980-09-18 | 1981-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-19 | 1984-09-18 | 1985-03-20 | $7700.00 | Window Closed / Lapsed |