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:
Mar. 31, 2015
Filed:
May. 11, 2012
Adam B. Eldredge, Austin, TX (US);
Xue-mei Gong, Austin, TX (US);
Adam B. Eldredge, Austin, TX (US);
Xue-Mei Gong, Austin, TX (US);
Silicon Laboratories Inc., Austin, TX (US);
Abstract
A frequency synthesizer capable of generating a clock signal having reduced digital spurs and reduced jitter is described. An apparatus includes a frequency modulator configured to generate a divide control signal and a digital quantization error signal in response to a divide ratio. The apparatus includes a phase modulator configured to generate a phase error signal based on the digital quantization error signal. The phase modulator is an n-order sigma-delta modulator module, n being an integer greater than one. The apparatus may include an interpolative divider configured to generate a feedback signal in a phase-locked loop (PLL) based on an output signal of the PLL, the divide control signal, and the phase error signal. The interpolative divider may include the frequency modulator and the phase modulator. The phase modulator may have a unity gain signal transfer function.