Patent attributes
A delta-sigma modulator coefficient calibration method and apparatus provides for adjustment of the modulator coefficients, and thus the modulator noise transfer function (NTF), in operational environments. A noise signal is injected into the feedback loop of the delta-sigma modulator either before or after the quantizer and the output of the modulator is correlated with the noise signal. The delta-sigma modulator has adjustable coefficients that are adjusted in conformity with the correlator output to achieve a more desirable noise transfer function. The correlator may include a tapped delay line and multiple correlators for simultaneously measuring each modulator coefficient directly, or may include a variable delay and a single correlator for measuring each coefficient sequentially.
