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. 01, 2005
Filed:
Sep. 23, 2003
John L. Melanson, Austin, TX (US);
Stephen T. Hodapp, Austin, TX (US);
Giri N. K. Rangan, Austin, TX (US);
John L. Melanson, Austin, TX (US);
Stephen T. Hodapp, Austin, TX (US);
Giri N. K. Rangan, Austin, TX (US);
Cirrus Logic, Inc., Austin, TX (US);
Abstract
A digital-to-analog converter ('DAC') system utilizes notch filters and chopping modulation technology to remove l/f and other baseband noise from a baseband of a signal of interest. Chopping modulation and demodulation circuitry of the DAC operate at a chopping frequency and all harmonics equal to approximately one-half of a digital input signal sampling frequency. A notch filter attenuates signals having frequencies around the chopping frequency prior to chopping to reduce fold back of noise into the baseband due to parasitic modulation. Another notch filter attenuating signals having frequencies around twice the chopping frequency further reduces fold back of noise into the baseband.