Title :
New method of phase noise and intermodulation distortion reduction in high-order QAM systems
Author :
Majewski, Janusz J.
Author_Institution :
SierraCom, Sierra Networks Inc., Hopkinton, MA, USA
Abstract :
Modern digital communication systems, such as microwave and millimeter wave point-to-point radios and local multipoint distribution system (LMDS) equipment now employ high-order quadrature amplitude modulation (QAM). In addition to the well known effect of additive white Gaussian noise (AWGN) on a QAM system´s performance, phase noise and 3rd order intermodulation distortion (IMD) can also be major contributors to system performance degradation. This paper presents a simple analog distortion cancellation method which consists of a low-frequency feedback circuit connected between the FET output (drain) and the input (gate). This low-frequency feedback integrated with active bias is used to reduce phase noise and 3rd order IMD product by approximately 7 dB
Keywords :
digital radio; feedback; field effect transistor circuits; interference suppression; intermodulation distortion; microwave links; network analysis; phase noise; quadrature amplitude modulation; 3rd order IMD; AWGN; FET input; FET output; LMDS; active bias; additive white Gaussian noise; analog distortion cancellation method; digital communication systems; high-order QAM systems; intermodulation distortion reduction; local multipoint distribution system; low-frequency feedback circuit; phase noise reduction; point-to-point radio; quadrature amplitude modulation; AWGN; Additive white noise; Digital communication; Intermodulation distortion; Microwave devices; Millimeter wave communication; Millimeter wave technology; Phase noise; Quadrature amplitude modulation; System performance;
Conference_Titel :
Microwaves, Radar and Wireless Communications. 2000. MIKON-2000. 13th International Conference on
Conference_Location :
Wroclaw
Print_ISBN :
83-906662-3-5
DOI :
10.1109/MIKON.2000.913920
