A primary delta-sigma modulator converts a continuous-time input signal into a discrete-time output sequence. A calibration circuit comprising an auxiliary delta-sigma modulator estimates percentage error in an integrator time constant and adjusts the time constant of at least one integrator in the primary...http://www.google.de/patents/US7321325?utm_source=gb-gplus-sharePatent US7321325 - Background calibration of continuous-time delta-sigma modulator
