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:
Jan. 11, 2005
Filed:
Apr. 29, 2003
Marjorie R. Plisch, Austin, TX (US);
John L. Melanson, Austin, TX (US);
Stephen T. Hodapp, Austin, TX (US);
Giri N. K. Rangan, Austin, TX (US);
Marjorie R. Plisch, 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 chopping modulation technology to remove 1/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 equal to approximately one-half of a digital input signal sampling frequency. Chopping at one-half the sampling frequency allows fold back into the baseband of the input signal's frequency components and reduces fold back of noise, such as quantization noise, residing outside the baseband. In a further embodiment, 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. Coordination of chopping timing also reduces noises in the output of the DAC system.