TY - CHAP A1 - Schubert, Martin J. W. T1 - Operational Amplifier Modeling Using Event-Driven VHDL T2 - IEEE/VIUF International Workshops on Behavioral Modeling and Simulation (BMAS'97), October 20/21 1997, Washington D.C., USA N2 - A method to model high-gain feedback-loop analog amplifiers on an event driven timeaxis is presented. The demonstrator is coded in digital VHDL’93. In the event-driven scheme any node in the network must converge „on its own“ based on the information delivered from its neighbors, as no overall matrix is set up. For this reason signalloops with a loop gain larger than one are typically unstable. This communication presents a numerically stable generic model for high gain amplifiers with a userdefined feedback network. Non-ideal effects like offset or finite gain can be taken into account. Y1 - 1997 UR - https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.495.5356&rep=rep1&type=pdf ER - TY - CHAP A1 - Bartsch, Ernst A1 - Schubert, Martin J. W. T1 - Mixed Analog-Digital Circuit Modeling Using Event-Driven VHDL T2 - IEEE/VIUF International Workshops on Behavioral Modeling and Simulation (BMAS'97), Ocotober 20/21 1997, Washington D.C., USA N2 - The mixed-signal event-driven (MixED) method developed to simulate small portions of analog circuitry within a digital environment is demonstrated in a mixed signal application. The MixED models using concurrent iteration to account for analog nodes were coded and run in standard VHDL’93. Networks containing linear components such as sources, resistors, capacitors, inductors and operational amplifiers are presented. The possibility to manipulate resistors during runtime is used to simulate switches. Y1 - 1997 UR - https://hps.oth-regensburg.de/scm39115/homepage/research/mixed/mixed_publications/1997_bmas_circuit.pdf ER - TY - CHAP A1 - Schubert, Martin J. W. T1 - Mixed Analog-Digital Signal Modeling Using Event-Driven VHDL T2 - X Brazilian Symposium on Integrated Circuit Design (SBCCI'97), August 25-27 1997, Porto Alegre, Brazil N2 - A method for solving networks containing generic analog components such as resistors, capacitors and inductors onan event driven time axis using digital VHDL is presented. The components are modeled as complex state machines communicating with their neighbors using INOUT type ports. The method takes advantage of simulation deltas to iterate without simulation-time consumption. A limited range of implicit equations can be solved this way. Y1 - 1997 UR - http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=50F6F0DA594FB90976CC1474581BC139?doi=10.1.1.508.3657&rep=rep1&type=pdf SP - 77 EP - 86 ER - TY - PAT A1 - Schubert, Martin J. W. T1 - Feedback-nach-Feedforward-Transformation zur Verhaltensmodellierung rückgekoppelter Verstärker Y1 - 1997 ER - TY - PAT A1 - Schubert, Martin J. W. T1 - Verfahren zur Simulation von Netzwerken auf einer ereignisgesteuerten Zeitachse mittels verteilter, lokaler Iteration Y1 - 1996 ER - TY - JOUR A1 - Schubert, Martin J. W. T1 - 70V-to-5V Differential CMOS Input Interface JF - IEE Electronic Letters Y1 - 1994 U6 - https://doi.org/10.1049/el:19940235 VL - 30 IS - 4 SP - 296 EP - 297 ER - TY - CHAP A1 - Schubert, Martin J. W. T1 - Mixed Signal Modeling in VHDL by Distributed Local Iteration T2 - VHDL Form, Toledo, Spain, April 20-24, 1997 Y1 - 1997 ER - TY - JOUR A1 - Lee, Wai-Kong A1 - Schubert, Martin J. W. A1 - Ooi, Boon Yaik A1 - Ho, Stanley Jian-Qin T1 - Multi-source energy harvesting and storage for floating wireless sensor network nodes with Long Range Communication Capability JF - IEEE Transactions on Industry Applications N2 - Wireless sensor networks are widely used for environmental monitoring in remote areas. They are mainly composed of wireless sensor nodes, usually powered by batteries with limited capacity, but are expected to communicate in long range and operate for extended time periods. To overcome these limitations, many energy harvesting techniques are proposed to power wireless nodes for prolonged operation, whereas multihop techniques are utilized to extend the communication range. In this paper, a novel floating device with multisource energy harvesting technology that can be used as a wireless sensor node is proposed. The long range communication between wireless sensor nodes and a gateway is established through LoRa technology. In addition to conventional solar panels, an energy harvesting technique based on thermoelectric generators exploiting thermal differences created between water surface and materials exposed to sunlight is proposed. Energy generated from photovoltaic and thermoelectric generators is combined to power the wireless sensor node. This floating device consumes 6.6216 Wh per day when used as a wireless sensor node for the collection and transmission of environmental data. The sensor node can operate on a water surface for at least 9.6 days when it is not exposed to sunlight. During a sunny day, the floating device can harvest 8.375 Wh from solar panels and 0.425 Wh from thermoelectric generation. In other words, the floating device harvests sufficient energy to be self-sustaining during sunny days. KW - Wireless sensor networks KW - Energy harvesting KW - floating device KW - LoRa KW - sensor node KW - solar energy KW - thermoelectric generation Y1 - 2018 U6 - https://doi.org/10.1109/TIA.2018.2799 VL - 54 IS - 3 SP - 2606 EP - 2615 PB - IEEE ER - TY - JOUR A1 - Schubert, Martin J. W. T1 - An Analog Node Model for VHDL Based Simulation of RF Integrated Circuits JF - IEEE Transactions on Circuits and Systems I, Regular Papers N2 - This paper describes a very-high-speed integrated-circuit hardware description language (VHDL)-based analog-node model, an associated driver component for the mixed-signal event-driven (MixED) simulation technique, and some primitive device models applied to radio-frequency integrated circuits. With the presented MixED method, analog circuits are modeled as a composition of controlled sources. Unlike other VHDL-based analog simulation methods, these MixED sources compute not only a real number representing an output voltage but also an output impedance. This allows the outputs of several MiXED sources to be connected in order to drive the same node signal n . The voltage of this record-type signal is automatically computed at its element n . u by resolution functions in compliance with Kirchhoff's current law. The data structure of the node signal n , its self-defined resolution functions, and an associated driver component are presented and discussed to meet different simulation requirements, such as speed, versatility, current accuracy, and adaptive time stepping. Several examples demonstrate how to behaviorally model mixed-signal components with this method with an emphasis on the simulation of a heterodyne receiver. Simulation speeds are compared to VHDL-AMS tools. KW - Integrated circuit modeling KW - Radio frequency KW - Analog integrated circuits KW - Radiofrequency integrated circuits KW - Computational modeling KW - Circuit simulation KW - Voltage KW - Signal resolution KW - Hardware design languages KW - Driver circuits Y1 - 2009 U6 - https://doi.org/10.1109/TCSI.2009.2027799 VL - 56 IS - 12 SP - 2717 EP - 2727 ER - TY - CHAP A1 - Schubert, Martin J. W. A1 - Seign, Stefan A1 - Dai, Q. A1 - Hinterseer, Sebastian A1 - Pielmeier, F. A1 - Pietsch, Alexander A1 - Seebauer, C. A1 - Weiß, Josef A1 - Yu, C. A1 - Zenger, Stefan T1 - Capacitive Sensor Technology for Soil Moisture Monitoring Networks T2 - 24th IEEE International Conference on Electronics, Circuits and Systems (ICECS), 5-8 Dec. 2017, Batumi, Georgia N2 - A sensor technology for tracking soil-moisture in agricultural fields is presented. A linear measurement method was developed to satisfy the need for cheap sensors with wide range of capacitance change such as factor 30. A combined wired and wireless network transmits data to a server. Various battery aspects are compared with respect to use in agriculture. Y1 - 2017 U6 - https://doi.org/10.1109/ICECS.2017.8292018 SP - 190 EP - 193 ER - TY - CHAP A1 - Schubert, Martin J. W. T1 - System Contemplations for Precision Irrigation in Agriculture T2 - AIP Conference Proceedings N2 - This communication contemplates political, biological and technical aspects for efficient and profitable irrigation in sustainable agriculture. A standard for irrigation components is proposed. The need for many, and three-dimensionally distributed, soil measurement points is explained, thus enabling the control of humidity in selected layers of earth. Combined wireless and wired data transmission is proposed. Energy harvesting and storage together with mechanical sensor construction are discussed. Y1 - 2017 SN - 9780735414969 U6 - https://doi.org/10.1063/1.4979393 VL - 1828 IS - 1 ER - TY - CHAP A1 - Schubert, Martin J. W. T1 - VHDL Based Simulation of a Delta-Sigma A/D Converter Clocked with a Phase-Locked Loop T2 - Design, Automation and Test in Europe, DATE'2001 Conference, March 13-16 2001, Munich N2 - The VHDL based mixed-signal event-driven (MixED) simulation method is employed to simulate a comprehensive system containing a number of mixed-signal building blocks: an analog waveform generator, a phase-locked loop and two ∆Σ modulators for A/D conversion. Y1 - 2001 UR - https://hps.hs-regensburg.de/~scm39115/homepage/research/mixed/mixed_publications/2001_date_pll_sigmadelta.pdf ER - TY - CHAP A1 - Schubert, Martin J. W. T1 - VHDL Based Simulation of a Sigma-Delta A/D Converter T2 - EEE/ACM International Workshop on Behavioral Modeling and Simulation (BMAS2000), October 19-20 2000, Orlando, Florida, USA, prodeedings N2 - The VHDL based mixed-signal event-driven (MixED) simulation method is employed to simulate a sigma-delta modulator for A/D conversion. Results are verified by experimental data and comparison to PSpice-AD simulations. Y1 - 2000 U6 - https://doi.org/10.1109/BMAS.2000.888367 ER - TY - CHAP A1 - Lee, Wai-Kong A1 - Schubert, Martin J. W. A1 - Ho, Stanley Jian-Qin T1 - Multi-source energy harvesting and storage for floating wireless-sensor-network nodes T2 - 2016 IEEE Industrial Electronics and Applications Conference (IEACon 2016), 20.-22. Nov. 2016, Kota Kinabalu, Malaysia Y1 - 2016 SN - 9781509009268 ER - TY - PAT A1 - Schubert, Martin J. W. A1 - Seign, Stefan T1 - Arrangement for Measuring Capacitance Y1 - 2016 ER - TY - JOUR A1 - Schubert, Martin J. W. A1 - Höfflinger, Bernd A1 - Schröder, D. A1 - Zingg, René P. T1 - 1D Modeling of SOI MOSFETs Using Distinct Quasi-Fermi Potentials JF - Microelectronic Engineering N2 - Distinct electron and hole quasi-Fermi potentials, øf,n and øf,p, are included into a one-dimensional SOI MOSFET model that accounts for finite inversion and depletion layer thicknesses. The inclusion of øf,n, øf,p in the nonlinear analytical model is demonstrated to describe phenomena like kink effect and the multistable-charge-controlled-memory effect (MCCM) in SOI MOSFETs. The calculation of øf,p(t) depends on the device history and generation/recombination rates. Y1 - 1991 U6 - https://doi.org/10.1016/0167-9317(91)90221-X VL - 15 IS - 1-4 SP - 237 EP - 240 ER - TY - CHAP A1 - Schubert, Martin J. W. A1 - Lee, Wai-Kong A1 - Ooi, Boon Yaik T1 - Quantization and Sampling Effects in Fast Digitally Controlled Switch-Mode DC/DC Buck Converters T2 - 2021 IEEE Industrial Electronics and Applications Conference (IEACon): 22.11.2021 - 23.11.2021, Penang, Malaysia N2 - Software-defined control of DC/DC switch mode power converters features unequaled flexibility compared to analog control. For fast switching converters as recently used for low power applications, digital control may cause steady-state oscillations known as limit cycles. This effect based on a quantized duty cycle is compared to other aberrations such as output ripple voltage, which is inherent to any pulse-width modulator. A distinction is made between DC and AC errors. The latter are divided into synchronous and asynchronous output voltage disturbances. Synchronous AC errors are composed of the switching frequency and its harmonics. KW - aberrations due to digitization KW - digital pulse-width modulation (DPWM) KW - low power DC/DC buck conversion KW - output voltage sampling Y1 - 2021 SN - 978-1-7281-9253-6 U6 - https://doi.org/10.1109/IEACon51066.2021.9654272 SP - 56 EP - 61 PB - IEEE ER -