Spectral Characteristics of the Double Loop Modulator

Mariam Motamed, Avideh Zakhor, Seth Sanders and TeWon Lee Department of Electrical Engineering and Computer Sciences University of California, Berkeley CA 94720 e-mail: [email protected], [email protected], and [email protected] ABSTRACT An important factor a ecting the performance of modulators is their tone behavior. A recent approach to alleviate the tone problem consists of moving the open loop poles outside the unit circle. In this paper, we determine the frequency location of two dominant tones as a function of pole location and obtain a partial characterization of the spectral shape. Audio testing along with a series of simulations are then performed to compare the e cacy of pole placement with that of the more traditional tone removal technique of dithering.