Adaptive design of delta sigma modulators

In this thesis, a genetic algorithm based on differential evolution (DE) is used to generate delta sigma modulator (DSM) noise transfer functions (NTFs). These NTFs outperform those generated by an iterative approach described by Schreier and implemented in the delsig Matlab toolbox. Several lowpass and bandpass DSMs, as well as DSM\u27s designed specifically for and very low intermediate frequency (VLIF) receivers are designed using the algorithm developed in this thesis and compared to designs made using the delsig toolbox. The NTFs designed using the DE algorithm always have a higher dynamic range and signal to noise ratio than those designed using the delsig toolbox

Sub-Nyquist Sampling: Bridging Theory and Practice

Sampling theory encompasses all aspects related to the conversion of continuous-time signals to discrete streams of numbers. The famous Shannon-Nyquist theorem has become a landmark in the development of digital signal processing. In modern applications, an increasingly number of functions is being pushed forward to sophisticated software algorithms, leaving only those delicate finely-tuned tasks for the circuit level. In this paper, we review sampling strategies which target reduction of the ADC rate below Nyquist. Our survey covers classic works from the early 50's of the previous century through recent publications from the past several years. The prime focus is bridging theory and practice, that is to pinpoint the potential of sub-Nyquist strategies to emerge from the math to the hardware. In that spirit, we integrate contemporary theoretical viewpoints, which study signal modeling in a union of subspaces, together with a taste of practical aspects, namely how the avant-garde modalities boil down to concrete signal processing systems. Our hope is that this presentation style will attract the interest of both researchers and engineers in the hope of promoting the sub-Nyquist premise into practical applications, and encouraging further research into this exciting new frontier.Comment: 48 pages, 18 figures, to appear in IEEE Signal Processing Magazin

RF measurements I: signal receiving techniques

For the characterization of components, systems and signals in the RF and microwave range, several dedicated instruments are in use. In this paper the fundamentals of the RF-signal sampling technique, which has found widespread applications in 'digital' oscilloscopes and sampling scopes, are discussed. The key element in these front-ends is the Schottky diode which can be used either as an RF mixer or as a single sampler. The spectrum analyser has become an absolutely indispensable tool for RF signal analysis. Here the front-end is the RF mixer as the RF section of modern spectrum analysers has a rather complex architecture. The reasons for this complexity and certain working principles as well as limitations are discussed. In addition, an overview of the development of scalar and vector signal analysers is given. For the determination of the noise temperature of a one-port and the noise figure of a two-port, basic concepts and relations are shown. A brief discussion of commonly used noise measurement techniques concludes the paper.Comment: 24 pages, contribution to the CAS - CERN Accelerator School: Specialised Course on RF for Accelerators; 8 - 17 Jun 2010, Ebeltoft, Denmar

Wireless Terahertz Communications: Optoelectronic Devices and Signal Processing

Novel THz device concepts and signal processing schemes are introduced and experimentally confirmed. Record-high data rates are achieved with a simple envelope detector at the receiver. Moreover, a THz communication system using an optoelectronic receiver and a photonic local oscillator is shown for the first time, and a new class of devices for THz transmitters and receivers is investigated which enables a monolithic co-integration of THz components with advanced silicon photonic circuits

New implementation of a GMSK demodulator in linear software radio receiver

This paper proposes a practical linear software-radio architecture (dealing with linear modulations) that is suitable for multi-mode operation. In particular, it is shown how to integrate GMSK into the proposed architecture. Coherent and noncoherent detections of GMSK signals are detailed for the implementation of the proposed software radio.published_or_final_versio