@inproceedings{Schubert, author = {Schubert, Martin J. W.}, title = {Mixed-Signal Event-Driven Simulation of a Phase-Locked Loop}, series = {IEEE/VIUF International Workshops on Behavioral Modeling and Simulation (BMAS'99), October 4-6 1999, Orlando, Florida, USA}, booktitle = {IEEE/VIUF International Workshops on Behavioral Modeling and Simulation (BMAS'99), October 4-6 1999, Orlando, Florida, USA}, abstract = {The mixed-signal event-driven (MixED) simulationalgorithm using standard VHDL is capable of modelinga number of analog and mixed-signal problems in digital circuits, e.g. RCL networks representing pads or wires, charge pumps, dynamic logic, voltage-controlledoscillators, phase-locked loops, etc. Important featuresare single-kernel simulation as well as rapid A/D andD/A interfacing. This paper demonstrates the simulation of a phase-locked loop (PLL), which is one of the most interesting applications of the MixED method. Many digital designs contain a PLL as only mixed-signal building block. The MixED method allows to simulate such designs with standard VHDL.}, language = {en} } @inproceedings{Schubert, author = {Schubert, Martin J. W.}, title = {VHDL Based Simulation of a Sigma-Delta A/D Converter}, series = {EEE/ACM International Workshop on Behavioral Modeling and Simulation (BMAS2000), October 19-20 2000, Orlando, Florida, USA, prodeedings}, booktitle = {EEE/ACM International Workshop on Behavioral Modeling and Simulation (BMAS2000), October 19-20 2000, Orlando, Florida, USA, prodeedings}, doi = {10.1109/BMAS.2000.888367}, abstract = {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.}, language = {en} } @inproceedings{Schubert, author = {Schubert, Martin J. W.}, title = {VHDL Based Simulation of a Delta-Sigma A/D Converter Clocked with a Phase-Locked Loop}, series = {Design, Automation and Test in Europe, DATE'2001 Conference, March 13-16 2001, Munich}, booktitle = {Design, Automation and Test in Europe, DATE'2001 Conference, March 13-16 2001, Munich}, abstract = {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.}, language = {en} } @article{Schubert, author = {Schubert, Martin J. W.}, title = {An Analog Node Model for VHDL Based Simulation of RF Integrated Circuits}, series = {IEEE Transactions on Circuits and Systems I, Regular Papers}, volume = {56}, journal = {IEEE Transactions on Circuits and Systems I, Regular Papers}, number = {12}, doi = {10.1109/TCSI.2009.2027799}, pages = {2717 -- 2727}, abstract = {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.}, language = {en} } @inproceedings{LeeSchubertHo, author = {Lee, Wai-Kong and Schubert, Martin J. W. and Ho, Stanley Jian-Qin}, title = {Multi-source energy harvesting and storage for floating wireless-sensor-network nodes}, series = {2016 IEEE Industrial Electronics and Applications Conference (IEACon 2016), 20.-22. Nov. 2016, Kota Kinabalu, Malaysia}, booktitle = {2016 IEEE Industrial Electronics and Applications Conference (IEACon 2016), 20.-22. Nov. 2016, Kota Kinabalu, Malaysia}, isbn = {9781509009268}, language = {en} } @inproceedings{Schubert, author = {Schubert, Martin J. W.}, title = {System Contemplations for Precision Irrigation in Agriculture}, series = {AIP Conference Proceedings}, volume = {1828}, booktitle = {AIP Conference Proceedings}, number = {1}, isbn = {9780735414969}, doi = {10.1063/1.4979393}, abstract = {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.}, language = {en} } @inproceedings{SchubertSeignDaietal., author = {Schubert, Martin J. W. and Seign, Stefan and Dai, Q. and Hinterseer, Sebastian and Pielmeier, F. and Pietsch, Alexander and Seebauer, C. and Weiß, Josef and Yu, C. and Zenger, Stefan}, title = {Capacitive Sensor Technology for Soil Moisture Monitoring Networks}, series = {24th IEEE International Conference on Electronics, Circuits and Systems (ICECS), 5-8 Dec. 2017, Batumi, Georgia}, booktitle = {24th IEEE International Conference on Electronics, Circuits and Systems (ICECS), 5-8 Dec. 2017, Batumi, Georgia}, doi = {10.1109/ICECS.2017.8292018}, pages = {190 -- 193}, abstract = {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.}, language = {en} } @misc{SchubertSeign, author = {Schubert, Martin J. W. and Seign, Stefan}, title = {Arrangement for Measuring Capacitance}, language = {en} } @article{Schubert, author = {Schubert, Martin J. W.}, title = {70V-to-5V Differential CMOS Input Interface}, series = {IEE Electronic Letters}, volume = {30}, journal = {IEE Electronic Letters}, number = {4}, doi = {10.1049/el:19940235}, pages = {296 -- 297}, language = {en} } @misc{Schubert, author = {Schubert, Martin J. W.}, title = {Verfahren zur Simulation von Netzwerken auf einer ereignisgesteuerten Zeitachse mittels verteilter, lokaler Iteration}, language = {de} } @inproceedings{Schubert, author = {Schubert, Martin J. W.}, title = {Mixed Signal Modeling in VHDL by Distributed Local Iteration}, series = {VHDL Form, Toledo, Spain, April 20-24, 1997}, booktitle = {VHDL Form, Toledo, Spain, April 20-24, 1997}, language = {en} } @inproceedings{Schubert, author = {Schubert, Martin J. W.}, title = {Mixed Analog-Digital Signal Modeling Using Event-Driven VHDL}, series = {X Brazilian Symposium on Integrated Circuit Design (SBCCI'97), August 25-27 1997, Porto Alegre, Brazil}, booktitle = {X Brazilian Symposium on Integrated Circuit Design (SBCCI'97), August 25-27 1997, Porto Alegre, Brazil}, pages = {77 -- 86}, abstract = {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.}, language = {en} } @misc{Schubert, author = {Schubert, Martin J. W.}, title = {Feedback-nach-Feedforward-Transformation zur Verhaltensmodellierung r{\"u}ckgekoppelter Verst{\"a}rker}, language = {de} } @inproceedings{Schubert, author = {Schubert, Martin J. W.}, title = {Operational Amplifier Modeling Using Event-Driven VHDL}, series = {IEEE/VIUF International Workshops on Behavioral Modeling and Simulation (BMAS'97), October 20/21 1997, Washington D.C., USA}, booktitle = {IEEE/VIUF International Workshops on Behavioral Modeling and Simulation (BMAS'97), October 20/21 1997, Washington D.C., USA}, abstract = {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.}, language = {en} } @inproceedings{BartschSchubert, author = {Bartsch, Ernst and Schubert, Martin J. W.}, title = {Mixed Analog-Digital Circuit Modeling Using Event-Driven VHDL}, series = {IEEE/VIUF International Workshops on Behavioral Modeling and Simulation (BMAS'97), Ocotober 20/21 1997, Washington D.C., USA}, booktitle = {IEEE/VIUF International Workshops on Behavioral Modeling and Simulation (BMAS'97), Ocotober 20/21 1997, Washington D.C., USA}, abstract = {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.}, language = {en} } @article{LeeSchubertOoietal., author = {Lee, Wai-Kong and Schubert, Martin J. W. and Ooi, Boon Yaik and Ho, Stanley Jian-Qin}, title = {Multi-source energy harvesting and storage for floating wireless sensor network nodes with Long Range Communication Capability}, series = {IEEE Transactions on Industry Applications}, volume = {54}, journal = {IEEE Transactions on Industry Applications}, number = {3}, publisher = {IEEE}, doi = {10.1109/TIA.2018.2799}, pages = {2606 -- 2615}, abstract = {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.}, language = {en} } @inproceedings{OoiLeeSchubertetal., author = {Ooi, Boon Yaik and Lee, Wai-Kong and Schubert, Martin J. W. and Ooi, Yu-Wei and Chin, Chee-Yang and Woo, Wing-Hon}, title = {A Flexible and Reliable Internet-of-Things Solution for Real-Time Production Tracking}, series = {IEEE Industrial Electronics and Applications Conference (IEACon): 22.11.2021 - 23.11.2021, Penang, Malaysia}, booktitle = {IEEE Industrial Electronics and Applications Conference (IEACon): 22.11.2021 - 23.11.2021, Penang, Malaysia}, publisher = {IEEE}, isbn = {978-1-7281-9253-6}, doi = {10.1109/IEACon51066.2021.9654672}, pages = {270 -- 275}, abstract = {The concept of Industrial Revolution 4.0 (IR4.0) has sparked the urgency of many manufacturers to revisit their manufacturing processes and search for opportunities to further improved their production output. Unfortunately, it is difficult to improve a process with inadequate data. Many of the SMEs in developing countries are still using manufacturing machines from the yesteryears which do not have computational and connectivity capabilities. Therefore, we developed an end-to-end Internet-of-Things (IoT) solution, which reliably tracks the production performance of manufacturing machines. This paper elaborates on the designs and the rationale behind it. As of the writing of this paper, our IoT system has been deployed in real manufacturing environment and has been running for approximately 90 days on a 24/7 basis without data lost.}, language = {en} } @inproceedings{SchubertLeeOoi, author = {Schubert, Martin J. W. and Lee, Wai-Kong and Ooi, Boon Yaik}, title = {Quantization and Sampling Effects in Fast Digitally Controlled Switch-Mode DC/DC Buck Converters}, series = {2021 IEEE Industrial Electronics and Applications Conference (IEACon): 22.11.2021 - 23.11.2021, Penang, Malaysia}, booktitle = {2021 IEEE Industrial Electronics and Applications Conference (IEACon): 22.11.2021 - 23.11.2021, Penang, Malaysia}, publisher = {IEEE}, isbn = {978-1-7281-9253-6}, doi = {10.1109/IEACon51066.2021.9654272}, pages = {56 -- 61}, abstract = {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.}, language = {en} } @inproceedings{SchubertHoefflingerZingg, author = {Schubert, Martin J. W. and H{\"o}fflinger, Bernd and Zingg, Ren{\´e} P.}, title = {A New Analytical Charge Model for the Dual-Gate-Controlled Thin-Film SOI MOSFET}, series = {Superlattices and Microstructures}, volume = {7}, booktitle = {Superlattices and Microstructures}, number = {4}, publisher = {Elsevier}, doi = {10.1016/0749-6036(90)90218-V}, pages = {323 -- 326}, abstract = {An analytical model for dual-gate-controlled SOI MOSFETs is presented, assuming uniformly doped p-silicon films. It is restricted to electron inversion layers and depletion regions, neglecting hole densities. It allows to account for the spatial description of electronic quantities in the silicon film. Due to the non-linearities of the semiconductor equations the model parameters must be extracted iteratively. Some applications are presented to demonstrate the usefulness of the model.}, language = {en} } @inproceedings{SchubertBloedelConradietal., author = {Schubert, Martin J. W. and Bl{\"o}del, J. and Conradi, P. and Lafosse, P. and Nebel, W. and Neusser, S. and Ryba, M. and Schr{\"o}der, D.}, title = {Extending EDIF for Technology Data}, series = {EDIF World Conference, 1989, San Jose, CA, USA, 11.-14. September}, booktitle = {EDIF World Conference, 1989, San Jose, CA, USA, 11.-14. September}, language = {en} }