Compensation technique for nonlinear distortion in RF circuits for multi-standard wireless systems

Chakrabarty, K. 2014. Compensation technique for nonlinear distortion in RF circuits for multi-standard wireless systems. PhD thesis University of Westminster Faculty of Science and Technology

TitleCompensation technique for nonlinear distortion in RF circuits for multi-standard wireless systems
TypePhD thesis
AuthorsChakrabarty, K.
Abstract

Recent technological advances in the RF and wireless industry has led to the design requirement of more sophisticated devices which can meet stringent specifications of bandwidth, data rate and throughput. These devices are required to be extremely sensitive and hence any external interference from other systems can severely affect the device and the output.

This thesis introduces the existing problem in nonlinear components in a multi-standard wireless system due to interfering signals and suggests potential solution to the problem. Advances in RF and wireless systems with emerging new communication standards have made reconfigurablility and tunability a very viable option. RF transceivers are optimised for multi-standard operation, where one band of frequency can act as an interfering signal to the other band. Due to the presence of nonlinear circuits in the transceiver chains such as power amplifiers, reconfigurable and tunable filters and modulators, these interfering signals produce nonlinear distortion products which can deform the output signal considerably. Hence it becomes necessary to block these interfering signals using special components.

The main objective of this thesis is to analyse and experimentally verify the nonlinear distortions in various RF circuits such as reconfigurable and tunable filters and devise ways to minimize the overall nonlinear distortion in the presence of other interfering signals. Reconfigurbality and tunablity in filters can be achieved using components such as varactor diodes, PIN diodes and optical switches. Nonlinear distortions in such components are measured using different signals and results noted.

The compensation method developed to minimize nonlinear distortions in RF circuits caused due to interfering signals is explored thoroughly in this thesis. Compensation method used involves the design of novel microstrip bandstop filters which can block the interfering signals and hence give a clean output spectrum at the final stage. Recent years have seen the emergence of electronic band gap technology which has “band gap” properties meaning that a bandstop response is seen within particular range of frequency. This concept was utilised in the design of several novel bandstop filters using defected microstrip structure. Novel tunable bandstop filters has been introduced in order to block the unwanted signal. Fixed single-band and dual-band filters using DMS were fabricated with excellent achieved results. These filters were further extended to tunable structures. A dual-band tunable filter with miniaturized size was developed and designed.

The designed filters were further used in the compensation technique where different scenarios showing the effect of interfering signals in wireless transceiver were described. Mathematical analysis proved the validation of the use of a bandstop filter as an inter-stage component. Distortion improvements of around 10dB have been experimentally verified using a power amplifier as device under test. Further experimental verification was carried out with a transmitter which included reconfigurable RF filters and power amplifier where an improvement of 15dB was achieved.

Year2014
FileKasturi_CHAKRABARTY_2014.pdf

Related outputs

Evaluation of nonlinear distortion in optically switchable UWB filters
Chakrabarty, K., Rabbi, K.M.F., Panagamuwa, C., Kodogiannis, V. and Budimir, D. 2014. Evaluation of nonlinear distortion in optically switchable UWB filters. Microwave and Optical Technology Letters. 56 (5), pp. 1092-1094. doi:10.1002/mop.28277

Linearity evaluation of optically reconfigurable UWB microstrip bandpass filter
Chakrabarty, K., Rabbi, K.M.F., Panagamuwa, C., Vardaxoglou, J.C. and Budimir, D. 2013. Linearity evaluation of optically reconfigurable UWB microstrip bandpass filter. 2013 IEEE International Symposium on Antennas and Propagation and USNC-URSI Nnational Radio Science Meeting. Lake Buena Vista, Florida, USA. July 7-12, 2013

Nonlinear distortion evaluation of reconfigurable RF circuits in wireless communication systems
Chakrabarty, K., Bukvic, B., Mohottige, N. and Budimir, D. 2013. Nonlinear distortion evaluation of reconfigurable RF circuits in wireless communication systems. SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC2013). Rio de Janeiro, Brazil 4 – 7 August 2013

Compact tunable bandstop filters using defected microstrip structure for multi-standard wireless systems
Chakrabarty, K. and Budimir, D. 2013. Compact tunable bandstop filters using defected microstrip structure for multi-standard wireless systems. 43rd European Microwave Conference (EuMC2013). Nuremberg, Germany October 6-11, 2013 pp. 1031-1034

Compact high linearity switchable dual-mode microstrip bandpass filters
Chakrabarty, K., Athukorala, L. and Budimir, D. 2011. Compact high linearity switchable dual-mode microstrip bandpass filters. IEEE Asia Pacific Microwave Conference (APMC2011). Melbourne, Australia 5-8 December 2011 pp. 2214-2220

Enhanced wireless transmitters using an inter-stage notch filter
Chakrabarty, K., Athukorala, L., Golubicic, Z. and Budimir, D. 2011. Enhanced wireless transmitters using an inter-stage notch filter. IEEE 10th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services (TELSIK2011). Nis, Serbia 05 - 08 Oct 2011

BBC World Service programme on microwaves
Budimir, D., Athukorala, L. and Chakrabarty, K. 2010. BBC World Service programme on microwaves.

Permalink - https://westminsterresearch.westminster.ac.uk/item/967w4/compensation-technique-for-nonlinear-distortion-in-rf-circuits-for-multi-standard-wireless-systems


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