Introduction to the special issue on IEEE-MWSCAS 2013

It is our pleasure to introduce this special issue on the 56th International IEEE Midwest Symposium on Circuits and Systems (MWSCAS) that was held in Columbus, OH, August 2013. Out of the 436 paper submissions from 36 countries, 372 papers were accepted for presentation in ten special lecture sessions, 38 regular lecture sessions, and 27 poster sessions. The theme of the conference was on ‘‘Advancing the Frontiers of Green Technology’’. In addition to the typical analog, digital and mixed signal circuits sessions, power management and energy harvesting sessions were particularly tied to the conference theme, The paper entitled ‘‘Design of High-Performance Integrated Dimmable LED Driver for High-Brightness SolidState Lighting Applications’’ by Zhidong Liu and Hoi Lee, was selected from that session to present a high-voltage dimmable LED driver in 0.35 lm technology for highbrightness solid-state lighting applications. The driver presented in the paper achieves significant improvements in power efficiency (peak efficiency of 98.8 %) and current accuracy. The improvement in efficiency was realized by eliminating the power diode and the sensing resistor in the power stage, thereby significantly reducing conduction losses in these components. A simultaneous peak and valley current sensing scheme is introduced in the paper to improve current sensing accuracy. The proposed scheme minimizes LED current errors under a wide range of input voltages and LEDs. Analog computer aided design (CAD) and circuit synthesis is a topic of considerable importance to the circuits and systems community (CAS). The paper by Reyad ElKhazali on the Biquadratic Approximation of FractionalOrder Laplacian Operators, introduces an improved algorithm to approximate the fractional Laplace operator. The presented biquadratic transfer function shows a flat phase characteristics with the frequency band of interest, with a bandwidth of approximation that can be extended by cascading several biquadratic modules. In addition to the several numerical examples given, the novel algorithm is also used for synthesizing fractional-order inductors and capacitors. For Analog to Digital Converters, two papers were selected for this special issue. In the paper by Simran Singh, Mikko Valkama, Michael Epp, Lauri Anttila, Wolfgang Schlecker, and Elmar Ingber, entitled, ‘‘Digital Correction of Frequency Response Mismatches in 2-Channel TimeInterleaved ADCs Using Adaptive I/Q Signal Processing’’, the authors propose a novel adaptive compensation architecture to address the frequency response mismatch of 2-channel time-interleaved ADCs. Time interleaved ADC (TI-ADC) are gaining a lot of momentum given the technological limitations on having a single core ADC running at high sampling rate without sacrificing resolution. However, the analog component variations and temperature drift within the parallel ADCs in TI-ADC introduce its own frequency dependent amplitude and phase mismatch, limiting the effective resolution and spurious free dynamic range (SFDR) of the ADC. In the paper, an adaptive method is proposed to detect the frequency response mismatch inside the frequency band of interest by utilizing digital I/Q mismatch estimation and correction algorithms. M. Hella (&) Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, 110 8th St., Troy, NY 12180, USA e-mail: hellam@ecse.rpi.edu