ECE (Circuits & Systems Group) at EFTF-IFCS 2017
The 31st European Frequency and Time Forum and the 71st consecutive meeting of the IEEE International Frequency Control Symposium were held as a joint conference in Besançon, France, on 9-13 July 2017. Circuits & Systems Group of ECE NTUA presented the following papers:
1. C. Basetas, P. P. Sotiriadis and N. Temenos, "Frequency synthesis using low-pass single-bit multi-step look-ahead sigma-delta modulators in quadrature upconversion scheme," 2017 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFC), BESANÇON, France, 2017, pp. 587-590.
Abstract: All-digital frequency synthesis using two low-pass single-bit Multi-Step Look-Ahead sigma-delta modultors (MSLA SDMs) is presented. MSLA SDMs provide better noise shaping characteristics, i.e. SNDR and bandwidth, than conventional SDMs at the cost of higher hardware complexity. The balance between complexity and performance is adjusted by the number of look-ahead steps, which is an additional design parameter. The frequency synthesizer system is comprised of two identical low-pass single-bit MSLA SDMs. Their inputs are orthogonal sinusoidals generated by a direct digital synthesizer (DDS). The frequency range of the synthesizer using a single clock signal is determined by the oversampling ratio (OSR) of the SDMs. A lower OSR results in a wider frequency range, but reduces the output SNDR. System-level simulation results of the frequency synthesizer are presented, showcasing the performance advantage of using MSLA SDMs instead of conventional ones.
Contact:
Charis Basetas: chbasetas[at]gmail[dot]com
Paul P. Sotiriadis: pps[at]ieee[dot]org
Nikos Temenos: ntemenos[at]gmail[dot]com
2. C. Basetas, P. P. Sotiriadis and N. Temenos, "Wide-band frequency synthesis using hardware-efficient band-pass single-bit multi-step look-ahead sigma-delta modulators," 2017 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFC), BESANÇON, France, 2017, pp. 591-594.
Abstract: Band-pass sigma-delta modulators (SDMs) can be used for all-digital frequency synthesis with low noise in the SDM passband. To avoid mixed-signal components such as DACs, a single-bit output is required. The noise shaping characteristics of single-bit sigma-delta modulators are limited by stability requirements. Look-ahead SDMs have been proposed to increase the bandwidth and signal-to-noise-and-distortion ratio (SNDR) of conventional single-bit ones. The cost is increased hardware complexity, but Multi-Step Look-Ahead sigma-delta modulators (MSLA SDMs) can significantly reduce the required hardware complexity, while retaining the advantages of look-ahead SDMs. This work demonstrates the hardware requirements of MSLA SDMs and proposes an all-digital frequency synthesizer architecture based on band-pass MSLA SDMs. The performance of the poposed synthesizer architecture is investigated for various configurations. Finally, the advantages of using MSLA SDMs instead of conventional single-bit ones in terms of bandwidth and SNDR are quantified.
Contact:
Charis Basetas: chbasetas[at]gmail[dot]com
Paul P. Sotiriadis: pps[at]ieee[dot]org
Nikos Temenos: ntemenos[at]gmail[dot]com
3. P. P. Sotiriadis, C. Basetas and N. Temenos, "32-QAM all-digital RF signal generator based on a homodyne sigma-delta modulation scheme," 2017 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFC), BESANÇON, France, 2017, pp. 603-604.
Abstract: An all-digital sigma-delta modulator (SDM) based RF synthesizer is presented. A multiplier-less architecture for the implementation of the band-pass SDM loop filter is proposed. Furthermore, this architecture enables the adjustment of the loop filter central frequency by exploiting homodyne up- and down-conversion. The RF synthesizer is comprised of a direct digital synthesizer (DDS) and the proposed multiplier-less single-bit band-pass SDM. Due to the simplicity of the synthesizer building blocks very high generated frequencies are possible. Modualtion is easily incorporated and as a test case its performance in a 32-QAM modulation scheme is presented.
Contact:
Paul P. Sotiriadis: pps[at]ieee[dot]org
Charis Basetas: chbasetas[at]gmail[dot]com
Nikos Temenos: ntemenos[at]gmail[dot]com