Title :
A modified LMS adaptive filter architecture with improved stability at RF
Author :
Aparin, Vladimir
Author_Institution :
QUALCOMM Inc., San Diego, CA, USA
Abstract :
Stability of a conventional LMS adaptive filter at RF is analyzed using the Laplace transform. It is shown that the RF signal delays along the filter feedback loop can make it unstable. A simple modification to the filter architecture is proposed to improve the loop phase margin. A practical implementation of the proposed architecture in 0.25μm CMOS technology is described. The designed filter is used as part of a cellular-band CDMA receiver to reject a transmitter signal leakage at the mixer input. It achieved the maximum rejection of 28dB.
Keywords :
CMOS analogue integrated circuits; Laplace transforms; adaptive filters; circuit stability; code division multiple access; least mean squares methods; mixers (circuits); radio receivers; 0.25 micron; CDMA receiver; CMOS technology; LMS adaptive filters; Laplace transforms; filter feedback loop; improved loop phase margin; signal delays; transmitter signal leakage; Adaptive filters; CMOS technology; Delay; Feedback loop; Laplace equations; Least squares approximation; Multiaccess communication; Radio frequency; Signal design; Stability analysis;
Conference_Titel :
Solid-State Circuits Conference, 2005. ESSCIRC 2005. Proceedings of the 31st European
Print_ISBN :
0-7803-9205-1
DOI :
10.1109/ESSCIR.2005.1541603
