Title :
Analysis of digital gain error compensation in continuous-time cascaded sigma-delta modulators
Author :
Keller, Matthias ; Buhmann, Alexander ; Ortmanns, Maurits ; Manoli, Yiannos
Author_Institution :
Dept. of Microsyst. Eng., Univ. of Freiburg, Freiburg
Abstract :
This paper deals with an in-depth analysis of digital gain error compensation in continuous-time cascaded Sigma-Delta modulators. Illustrated by the example of a 2-1 cascaded modulator, it will be shown that this approach always restores the desired noise-shaping characteristic in cases where, except for the first stage, only first-order modulators are used in the cascade. However, a leakage term still exists which may increase the total in-band noise in case the first integrator of any stage in the cascade exhibits a gain variation. For any other architecture, the digital correction approach fails to truly compensate for gain errors as illustrated by the example of a 2-2 cascaded modulator. Low-order shaped quantization noise may then still determine the total in-band noise.
Keywords :
error analysis; error compensation; modulators; sigma-delta modulation; 2-2 cascaded modulator; continuous-time cascaded sigma-delta modulators; digital correction approach; digital gain error compensation analysis; first-order modulators; in-band noise; low-order shaped quantization noise; Capacitors; Delta-sigma modulation; Digital modulation; Error compensation; Frequency; Microelectronics; Noise cancellation; Noise shaping; Quantization; Resistors;
Conference_Titel :
Circuits and Systems, 2008. ISCAS 2008. IEEE International Symposium on
Conference_Location :
Seattle, WA
Print_ISBN :
978-1-4244-1683-7
Electronic_ISBN :
978-1-4244-1684-4
DOI :
10.1109/ISCAS.2008.4541807