ECE (Circuits & Systems Group) at MOCAST 2017
The 6th International Conference on Modern Circuits and Systems Technologies (MOCAST) took place on 4-6 May 2017 in Thessaloniki, Greece. Circuits & Systems Group of ECE NTUA presented the following papers:
1. D. Baxevanakis and P. P. Sotiriadis, ”A 1.8V CMOS chopper four-quadrant analog multiplier,” 2017 6th International Conference on Modern Circuits and Systems Technologies (MOCAST), Thessaloniki, 2017, pp. 1-4.
doi: 10.1109/MOCAST.2017.7937649
Abstract: A 1.8V CMOS chopper four-quadrant analog multiplier, intending to serve as an autonomous IC block for low-frequency signal processing, is presented. Particular emphasis is laid upon achieving low output noise by means of chopper stabilization, while the multiplier’s operation is based on the MOS Translinear Principle. The proposed design has been implemented and simulated in TSMC 0.18 μm CMOS process.
Contact:
Dimitrios Baxevanakis: dimbaxev[at]central[dot]ntua[dot]gr
Paul P. Sotiriadis: pps[at]ieee[dot]org
2. C. Dimas, P. Tsampas, N. Ouzounoglou and P. P. Sotiriadis, ”Development of a modular 64-electrodes Electrical Impedance Tomography system,” 2017 6th International Conference on Modern Circuits and Systems Technologies (MOCAST), Thessaloniki, 2017, pp. 1-4.
doi: 10.1109/MOCAST.2017.7937666
Abstract: The design and implementation of an Electrical Impedance Tomography system with 64 electrodes placed on a 2-D circular pattern is presented. The system’s architecture and the algorithm for solving the reverse E/M problem and deriving the conductivity distribution are discussed. Experimental measurements are presented confirming the proper operation.
Contact:
Christos Dimas: chdim[at]central[dot]ntua[dot]gr
Petros Tsampas: ptsampas[at]yahoo[dot]gr
Nikolaos Ouzounoglou: nikolaos.uzunoglou[at]gmail[dot]com
Paul P. Sotiriadis: pps[at]ieee[dot]org
3. C. Basetas and P. P. Sotiriadis, ”The class of 1-bit Multi-Step Look-Ahead ΣΔ modulators and their applications,” 2017 6th International Conference on Modern Circuits and Systems Technologies (MOCAST), Thessaloniki, 2017, pp. 1-4.
doi: 10.1109/MOCAST.2017.7937677
Abstract: The class of 1-bit Multi-Step Look-Ahead (MSLA) ΣΔ modulators is presented. They take into account current and future quantization errors improving upon the stability and noise shaping characteristics of conventional 1-bit ΣΔ modulators. The MSLA modulator system is found to be equivalent to a number of parallel conventional ΣΔ modulators sharing a multi-input 1-bit quantizer. The number of look-ahead steps along with other design parameters enable fine-tuning of performance vs. hardware complexity according to the application. The performance of MSLA modulators for various design parameter values is investigated, highlighting their advantages in a multitude of applications like digital transmitters, class-D power amplifiers and DACs.
Contact:
Charis Basetas: chbasetas[at]gmail[dot]com
Paul P. Sotiriadis: pps[at]ieee[dot]org
4. N. Hadjigeorgiou, E. Hristoforou and P. P. Sotiriadis, ”Closed-loop current-feedback, signal-chopped, low noise AMR sensor with high linearity,” 2017 6th International Conference on Modern Circuits and Systems Technologies (MOCAST), Thessaloniki, 2017, pp. 1-4.
doi: 10.1109/MOCAST.2017.7937679
Abstract: Over the past twenty years’ magnetic sensors have emerged as a preferred choice in many sensory systems due to their high accuracy, reliability and mechanical robustness. This has sparked the development of different types of magnetic sensors for magnetic field measurements as well as for measuring other quantities indirectly. Sensitivity, linearity, signal-to-noise ratio, measurement range and cross-talk between sensors in multi-axis / multi-sensor applications are only some of the magnetic sensor’s characteristics that have been studied in the past. The aim of this paper is to present a fully analog current-feedback closed loop system for AMR (Anisotropic Magnetic Resistance) magnetic sensors. The calibration and testing were conducted in a 3D Helmholtz coil setup capable of controlling the magnetic field amplitude and direction in the AMR sensor area. The noise characterization was realized in a multilayer tube of soft magnetic material. Thorough experimental characterization and testing indicates that the proposed close loop architecture improves sensor’s linearity while maintaining low noise level.
Contact:
Neoklis Hadjigeorgiou: nhatzig[at]central[dot]ntua[dot]gr
Evangelos Hristoforou: hristoforou[at]ece[dot]ntua[dot]gr
Paul P. Sotiriadis: pps[at]ieee[dot]org
5. P. P. Sotiriadis and C. Basetas, ”All-digital single-bit-output RF transmitters using homodyne sigma-delta modulation,” 2017 6th International Conference on Modern Circuits and Systems Technologies (MOCAST), Thessaloniki, 2017, pp. 1-4.
doi: 10.1109/MOCAST.2017.7937680
Abstract: An all-digital RF transmitter architecture capable of driving directly a switching RF power amplifier and therefore without the need of a high-speed RF DAC is presented. Modulation is achieved by directly modulating a direct digital synthesizer (DDS) generated signal. The proposed architecture is based on single-bit sigma-delta modulation using the introduced homodyne band-pass filter topology, which allows for the adjustment of its central frequency without changing its coefficients. This is achieved by using variable frequency homodyne down- and up-conversion along with a low-pass filter with fixed coefficients. Furthermore, a multiplier-less homodyne filter topology is shown to be possible, greatly reducing the hardware requirements for its implementation. MATLAB simulation results are presented based on a 64-QAM modulation scheme demonstrating the capabilities of the proposed architecture.
Contact:
Paul P. Sotiriadis: pps[at]ieee[dot]org
Charis Basetas: chbasetas[at]gmail[dot]com
6. K. Touloupas, C. Basetas and P. P. Sotiriadis, ”Derivation of the transfer functions of 1-bit Multi-Step Look-Ahead ΣΔ modulators using system identification methods,” 2017 6th International Conference on Modern Circuits and Systems Technologies (MOCAST), Thessaloniki, 2017, pp. 1-4.
doi: 10.1109/MOCAST.2017.7937690
Abstract: A method to calculate the transfer functions of Multi-Step Look-Ahead (MSLA) ΣΔ modulators is presented. MSLA ΣΔ modulators exhibit better noise shaping characteristics and stability than conventional ones. They are comprised of a number of conventional ΣΔ modulators in parallel, sharing a multi-input 1-bit output quantizer. MSLA modulators are highly nonlinear systems due to the multi-input quantizer. Modeling of the quantizer using conventional linearization methods does not give satisfactory results. Therefore, this work applies system identification methods to derive the linearized MSLA modulator system transfer functions. More specifically the Vector Fitting algorithm is used for the linearization of a number of MSLA modulators. The obtained transfer functions are in very good agreement with simulation results, showcasing the effectiveness of the applied methods.
Contact:
Kostas Touloupas: kostastoulou[at]gmail[dot]com
Charis Basetas: chbasetas[at]gmail[dot]com
Paul P. Sotiriadis: pps[at]ieee[dot]org