Pulse or digital communications – Pulse code modulation – Differential
Reexamination Certificate
2005-01-11
2005-01-11
Vo, Don N. (Department: 2631)
Pulse or digital communications
Pulse code modulation
Differential
C341S143000
Reexamination Certificate
active
06842486
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.
REFERENCES:
patent: 4138649 (1979-02-01), Schaffer
patent: 4939516 (1990-07-01), Early
patent: 5039989 (1991-08-01), Welland et al.
patent: 5148167 (1992-09-01), Ribner
patent: 5561660 (1996-10-01), Kotowski et al.
patent: 20040021594 (2004-02-01), Melanson
Hodapp Stephen T.
Melanson John L.
Plisch Marjorie R.
Rangan Giri N. K.
Chambers Kent B.
Cirrus Logic Inc.
Hamilton & Terrile LLP
Vo Don N.
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