US3710276A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital variable quadrature sine wave voltage controlled oscillator
Assignee: Ampex Corp
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Filing: 1971-06-01
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Granted: 1973-01-09
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Expires: 1991-06-01
Abstract
Abstract A pulse voltage controlled oscillator running at four times the desired frequency f triggers a two stage shift register which has an inverted feedback loop. The outputs of both stages are similar square waves of frequency f, and they are set at a 90* phase difference of each other. Since a square wave of frequency f possesses only harmonics of odd orders, a low pass filter which rejects 3f can admit a square wave frequency varying between f and 3f. A pair of identical filters coupled to the outputs of respective shift register stages provide output signals of corresponding frequency which are 90* out of phase. For a frequency range extending between 3f and 9f, another pair of filters are required, etc. Additional shift registers may be added to the two stage shift register to provide output signals with a phase shift equal to the corresponding fraction of 360*.
Inventors
- 👤 T Dao
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 07:52
CPC Classifications
H; H03; H03B; H03B27/00
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
80 words
A digital variable quadrature sine wave generator comprising; a source of pulses; shift register means coupled to the source of pulses and including inverted feedback means to generate at least a pair of square waves having a selected constant phase difference and identical frequencies; filter means of selected frequency bandpass coupled to the shift register means to generate a pair of sine waves having equal and constant amplitudes and identical frequencies, said frequency being equal to the square wave frequency.
Claim 2
Dependent Claim
80 words
A digital variable quadrature sine wave generator comprising; a source of pulses; shift register means coupled to the source of pulses and including inverted feedback means to generate at least a pair of square waves having a selected constant phase difference and identical frequencies; filter means of selected frequency bandpass coupled to the shift register means to generate a pair of sine waves having equal and constant amplitudes and identical frequencies, said frequency being equal to the square wave frequency.
Claim 3
Dependent Claim
54 words
The sine wave generator of claim 1 wherein the source of pulses has a frequency 4f; the shift register means generates the pair of square waves at a frequency f at the selected phase difference; and the filter means includes a pair of identical filters of bandpass frequency equal to from f to 3f.
Claim 4
Dependent Claim
92 words
The sine wave generator of claim 2 wherein the shift register means includes at least two stages of shift registers each having ''''set'''' and ''''reset'''' inputs and ''''Q'''' and ''''Q'''' outputs; wherein the first stage register ''''Q'''' and ''''Q'''' are operatively coupled to the last stage register ''''set'''' and ''''reset'''' inputs respectively; the last stage register outputs ''''Q'''' and ''''Q'''' are inverted and operatively coupled to the ''''reset'''' and ''''set'''' inputs of the first stage register respectively; and said square waves are taken from the ''''Q'''' outputs of the shift registers respectively.
Claim 5
Dependent Claim
89 words
The sine wave generator of claim 3 further including an additional shift register directly coupled between said two stages of shift registers to provide an additional square wave output of equal amplitude and frequency, wherein the phase difference between the square waves is constant and equal to 180* divided by the number of stages; and a third identical filter of frequency range between f and 3f coupled to the additional shift register, said three filters defining equal and constant amplitude sine waves of equal frequencies having said phase difference.
Claim 6
Dependent Claim
25 words
The sine wave generator of claim 3 wherein the filter means includes a pair of filters of bandpass frequency equal to from 3f to 9f.
References Cited (Backward Citations)
US3529260A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-09 | 1976-07-10 | 1977-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-09 | 1980-07-10 | 1981-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-09 | 1984-07-10 | 1985-01-09 | $7700.00 | Window Closed / Lapsed |