Design and implementation of generalized topologies of time-interleaved variable bandpass Σ−Δ modulators

Kalafat Kizilkaya, I. 2016. Design and implementation of generalized topologies of time-interleaved variable bandpass Σ−Δ modulators. PhD thesis University of Westminster Engineering

TitleDesign and implementation of generalized topologies of time-interleaved variable bandpass Σ−Δ modulators
TypePhD thesis
AuthorsKalafat Kizilkaya, I.
Abstract

In this thesis, novel analog-to-digital and digital-to-analog generalized time-interleaved variable bandpass sigma-delta modulators are designed, analysed, evaluated and implemented that are suitable for high performance data conversion for a broad-spectrum of applications. These generalized time-interleaved variable bandpass sigma-delta modulators can perform noise-shaping for any centre frequency from DC to Nyquist. The proposed topologies are well-suited for Butterworth, Chebyshev, inverse-Chebyshev and elliptical filters, where designers have the flexibility of specifying the centre frequency, bandwidth as well as the passband and stopband attenuation parameters. The application of the time-interleaving approach, in combination with these bandpass loop-filters, not only overcomes the limitations that are associated with conventional and mid-band resonator-based bandpass sigma-delta modulators, but also offers an elegant means to increase the conversion bandwidth, thereby relaxing the need to use faster or higher-order sigma-delta modulators.

A step-by-step design technique has been developed for the design of time-interleaved variable bandpass sigma-delta modulators. Using this technique, an assortment of lower- and higher-order single- and multi-path generalized A/D variable bandpass sigma-delta modulators were designed, evaluated and compared in terms of their signal-to-noise ratios, hardware complexity, stability, tonality and sensitivity for ideal and non-ideal topologies. Extensive behavioural-level simulations verified that one of the proposed topologies not only used fewer
coefficients but also exhibited greater robustness to non-idealties.

Furthermore, second-, fourth- and sixth-order single- and multi-path digital variable bandpass digital sigma-delta modulators are designed using this technique. The mathematical modelling and evaluation of tones caused by the finite wordlengths of these digital multi-path sigmadelta modulators, when excited by sinusoidal input signals, are also derived from first principles and verified using simulation and experimental results. The fourth-order digital variable-band sigma-delta modulator topologies are implemented in VHDL and synthesized on Xilinx® SpartanTM-3 Development Kit using fixed-point arithmetic. Circuit outputs were taken via RS232 connection provided on the FPGA board and evaluated using MATLAB routines developed by the author. These routines included the decimation process as well. The experiments undertaken by the author further validated the design methodology presented in the work.

In addition, a novel tunable and reconfigurable second-order variable bandpass sigma-delta modulator has been designed and evaluated at the behavioural-level. This topology offers a flexible set of choices for designers and can operate either in single- or dual-mode enabling multi-band implementations on a single digital variable bandpass sigma-delta modulator.

This work is also supported by a novel user-friendly design and evaluation tool that has been developed in MATLAB/Simulink that can speed-up the design, evaluation and comparison of analog and digital single-stage and time-interleaved variable bandpass sigma-delta modulators. This tool enables the user to specify the conversion type, topology, loop-filter type, path number and oversampling ratio.

Year2016
FileKizilkaya_Isil_thesis.pdf

Related outputs

Design and Implementation of Novel FPGA Based Time-Interleaved Variable Centre-Frequency Digital Sigma-Delta Modulators
Kalafat Kizilkaya, I., Al-Janabi, M. and Kale, I. 2015. Design and Implementation of Novel FPGA Based Time-Interleaved Variable Centre-Frequency Digital Sigma-Delta Modulators. Special Issue of ACTA IMEKO Journal. 4 (1), pp. 68-76.

Novel Time-Interleaved Variable-Center Frequency Σ-∆ Modulators - Design, Analysis and Critical Evaluation
Kalafat Kizilkaya, I., Al-Janabi, M. and Kale, I. 2013. Novel Time-Interleaved Variable-Center Frequency Σ-∆ Modulators - Design, Analysis and Critical Evaluation. IEEE Instrumentation and Measurement Technology Conference. Minneapolis, USA 06 May 2013

Design and Evaluation of Time-Interleaved Variable Center-Frequency Sigma-Delta Modulators
Kalafat Kizilkaya, I., Al-Janabi, M. and Kale, I. 2013. Design and Evaluation of Time-Interleaved Variable Center-Frequency Sigma-Delta Modulators. 18th International Conference on Digital Signal Processing. Santorini, Greece 01 Jul 2013 IEEE . doi:10.1109/ICDSP.2013.6622778

Permalink - https://westminsterresearch.westminster.ac.uk/item/9x24v/design-and-implementation-of-generalized-topologies-of-time-interleaved-variable-bandpass-modulators


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