Title :
A compensation method of the excess loop delay in continuous-time complex sigma-delta modulators
Author :
Kim, Song-Bok ; Joeres, Stefan ; Heinen, Stefan
Author_Institution :
Dept. of Integrated Analog Circuits, RWTH Aachen Univ., Aachen
Abstract :
Continuous-time (CT) SigmaDelta modulators seriously suffer from excess loop delay, which can not be seen in discrete-time designs. In this paper, it is shown that excess loop delay decreases the signal-to-noise ratio (SNR), input dynamic range (DR) and stability in CT complex SigmaDelta modulator with CIFF topology. A method for its compensation is presented. The proposed compensation scheme has a unity delay in front of the quantizer and complex compensation coefficients which are determined by analysis of the ideal DT loop filter transfer function. The simulation results are compared to analytical considerations.
Keywords :
compensation; discrete time filters; sigma-delta modulation; signal processing; transfer functions; CIFF topology; DT loop filter transfer function; compensation method; complex compensation coefficients; continuous-time complex sigma-delta modulators; discrete-time designs; dynamic range; excess loop delay; signal-to-noise ratio; Analog circuits; Delay effects; Delta-sigma modulation; Feedback loop; Filters; Noise shaping; Optical signal processing; Signal to noise ratio; Topology; Transfer functions;
Conference_Titel :
Circuit Theory and Design, 2007. ECCTD 2007. 18th European Conference on
Conference_Location :
Seville
Print_ISBN :
978-1-4244-1341-6
Electronic_ISBN :
978-1-4244-1342-3
DOI :
10.1109/ECCTD.2007.4529556
