Coded data generation or conversion – Analog to or from digital conversion – Differential encoder and/or decoder
Reexamination Certificate
2005-03-01
2005-03-01
Tokar, Michael (Department: 2819)
Coded data generation or conversion
Analog to or from digital conversion
Differential encoder and/or decoder
C341S144000, C341S118000, C341S120000, C375S247000, C702S064000
Reexamination Certificate
active
06861968
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.
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Hodapp Stephen T.
Melanson John L.
Rangan Giri N. K.
Chambers Kent B.
Cirrus Logic Inc.
Hamilton & Terrile LLP
Mai Lam T.
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