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The Scientific World Journal
Volume 2014 (2014), Article ID 521717, 8 pages
http://dx.doi.org/10.1155/2014/521717
Research Article

A Low-Noise Delta-Sigma Phase Modulator for Polar Transmitters

School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China

Received 26 November 2013; Accepted 17 January 2014; Published 25 February 2014

Academic Editors: P. Colantonio and F. L. Tofoli

Copyright © 2014 Bo Zhou. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A low-noise phase modulator, using finite-impulse-response (FIR) filtering embedded delta-sigma (ΔΣ) fractional-N phase-locked loop (PLL), is fabricated in 0.18 μm CMOS for GSM/EDGE polar transmitters. A simplified digital compensation filter with inverse-FIR and -PLL features is proposed to trade off the transmitter noise and linearity. Experimental results show that the presented architecture performs RF phase modulation well with 20 mW power dissipation from 1.6 V supply and achieves the root-mean-square (rms) and peak phase errors of 4° and 8.5°, respectively. The measured and simulated phase noises of −104 dBc/Hz and −120 dBc/Hz at 400-kHz offset from 1.8-GHz carrier frequency are observed, respectively.