The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 03, 1991
Filed:
Mar. 14, 1990
Christopher P Summers, London, GB;
U.S. Philips Corporation, New York, NY (US);
Abstract
A digital oscillator produces a succession of numbers from which a periodic analogue waveform is produced. These numbers represent a triangular waveform (or a sine waveform). Their direct conversion into analogue form by a digital-to-analogue converter, followed by integration by an integrator produces a distorted analogue waveform SW which when limited by a limiter produces an output pulse waveform with an inaccurate mark/space ratio. A subtraction circuit 2 subtracts each number produced by the digital pulse generator from the previous number, to produce a series of new numbers which represent a pre-distorted waveform. When these new numbers are converted into analogue form, the integration of the resulting waveform by the integrator produces an analogue waveform with clearly defined zero crossings. The output pulse waveform is thereby given a relatively constant mark/space ratio. Furthermore, when the pulse generator is driven by a clock whose frequency is several times greater than the frequency of the output pulse waveform, the latter suffers only small phase modulation (jitter).