Bernd Deutschmann

Methodology to Predict EME Effects in CAN Bus Systems Using VHDL-AMS

The electromagnetic emissions (EME) of integrated circuits (ICs) are of increasing importance in the selection of automotive components. Although the IC is treated as the main cause for these emissions, the electrical environment, i.e., the application of an IC including the minimal circuitry on the application board and its layout, as well as the global connection terminals (i.e., supply pins and bus signals) representing the load of an IC are crucial in determining the emission behavior of the entire system. This paper provides application engineers information about different aspects related to the EME of a controller area network (CAN) bus system and how emissions are generated and transformed within the application environment. It presents a methodology to investigate and predict the effects by using Very High-Speed IC Hardware Description Language-Analog Mixed Signal (VHDL-AMS). The description focuses on the interaction between the CAN transceivers and the twisted pair transmission line connecting them. Both common mode and differential mode as well as mode conversion aspects are considered. It highlights the fact that EMEs from a CAN bus system highly depend on the application environment.

EMI-receiver simulation model with quasi-peak detector

Computer aided design and simulations are an integral part in the development process of integrated circuits. In order to evaluate the electromagnetic compatibility (EMC) of integrated circuits in simulation, simulation models of the EMC measurement setup and the EMC measurement device are needed. In this work, an electromagnetic interference (EMI) receiver simulation model is presented. The EMI-reciever simulation model is intended to analyze electromagnetic emission (EME) of integrated circuits from transient simulations. The model is explained in detail and emulates an CISPR-16 conform test receiver. It is implemented using an STFT algorithm, and evaluates simulation output in CISPR Band-B/C/D with peak, average and quasi-peak detector. A quasi-peak detector model for pulsed disturbances is described, that significantly reduces simulation time compared to traditional implementations. The presented EMI-receiver model is verified with different test setups.

Energy harvesting with on-chip solar cells and integrated DC/DC converter

In this paper an energy-autonomous fully integrated photovoltaic driven harvesting solution for wireless sensor node applications is proposed. Photo diodes in parallel connection are used as on-chip micro solar cells. In order to provide the highest efficiency for ambient harvesting purposes, the n-well to p-substrate junction, which gives a negative voltage related to the p-substrate, is used. A test chip in a 130 nm CMOS technology, with different solar-cell configurations was designed and investigated. Numerous performance measurements were carried out in order to compare the on-chip solar cells. The achieved fill factor is 78% at 25 klux and 42°C. A charge pump circuit including a flying capacitor driver which allows the usage of the generated negative voltage is also presented.

Electromagnetic evaluation of Class-D switching schemes

Class-D audio amplifiers may significantly contribute to the electromagnetic emissions of electronic devices. This work deals with the electromagnetic emissions created by Class-D amplifier output stages. Output stage switching schemes of traditional and filterless Class-D amplifiers are analyzed concerning their ability to create electromagnetic disturbances. Three different switching schemes are compared, namely Class-AD, Class-BD, and Ternary switching. Finally, commercially available Class-D amplifier ICs are measured and compared using an electromagnetic compatibility measurement setup according to IEC61967-4-A1.

Analysis of conducted emissions in CAN bus systems with VHDL-AMS

The increasing number of electronic components in a motor vehicle makes the prediction of EMC behavior more and more crucial. Thus, early in the design phase new methodologies are being implemented in order to estimate conducted emissions. This paper provides application engineers information about the different aspects to electromagnetic emissions of a CAN bus system; how emissions are generated and transformed within the application environment. Behavioral models (VHDL-AMS) are used for system simulations. The description focuses on the interaction between CAN transceivers and the twisted pair transmission line connecting them. Both common- and differential-mode as well as mode conversion aspects are considered. It highlights the fact that electromagnetic emissions from a CAN bus system highly depend on the application environment.

On the Robustness of CMOS-Chopped Operational Amplifiers to Conducted Electromagnetic Interferences

This paper deals with the robustness of low power chopped CMOS operational amplifiers (OpAMPs) to electromagnetic interferences (EMI) conducted at the device input stage. The main differences between chopped amplifiers and standard offset uncompensated ones are analyzed in terms of EMI susceptibility, achieving three main results. First, a new model is developed to show how chopping influences the amplifier susceptibility in a broadband sense, demonstrating that chopped OpAMPs generate a lower amount of EMI-induced offset from the nonlinear distortion with respect to standard ones because of the topological differences between the respective input stages. Second, a model to predict the effects of EMI appearing at the multiples of the chopping frequency is derived, showing that chopped OpAMPs can experience dc shift peaks because of the linear distortion of the disturbances whose frequencies hit the even multiples of the chopping frequency. Finally, the simultaneous presence of the technological offset and the offset produced by the nonlinear and the linear distortion of EMI in chopped OpAMP is illustrated by means of dedicated EMI susceptibility measurements performed on several devices designed to validate the analysis.

Effects of single tone RF interferences on chopped operational amplifiers

This paper deals with the susceptibility of analog integrated circuits to radio frequency interferences (RFI) and it concentrates on the effects induced by RFI on the operation of offset compensated chopped CMOS operational amplifiers. The first part of the work explains the causes of the additional output DC offset induced by input RF disturbances in chopped systems. Afterwards, the design of a chopped CMOS operational transconductance amplifier (OTA) is briefly treated and in the final part of the paper the results of some simulations performed on such OTA are presented in order to highlight the concepts discussed in the first and second paragraphs.

Design and theoretical comparison of input ESD devices in 180 nm CMOS with focus on low capacitance

With the last decade’s advances in sensor technologies and packaging techniques, there are several applications where the input capacitance and the leakage current of the integrated circuit (IC) front-end limit the readout accuracy of sensor systems. In particular, optimization of the electrostatic discharge (ESD) protection devices at the IC input could improve performance. Specifically, such optimization should involve reduction of parasitic capacitance and leakage current while maintaining the ESD robustness. Several ESD devices have been analyzed against input capacitance, leakage current and robust ESD performance. The first device of interest is a diode, as the simplest solution and then there are three MOS transistor based devices, gate-grounded NMOS (GGNMOS), gate-coupled NMOS (GCNMOS), and substrate pump NMOS (SPNMOS). The target fabrication process is 180 nm CMOS. Theoretical analysis of capacitance simulated with Cadence® in 180 nm CMOS design kit including layout extracted parasitics in combination with TCAD Sentaurus® simulations of current density and temperature is presented for selected ESD devices.ZusammenfassungMit den Fortschritten des letzten Jahrzehnts in Sensor- und IC-Package-Technologien gibt es vermehrt Anwendungen, bei denen die Eingangskapazität und der Leckstrom des integrierten Schaltkreises (ICs) die Auslesegenauigkeit von Sensorsystemen begrenzen. Eine entsprechende Optimierung der Schutzstrukturen gegen elektrostatische Entladungen (ESD) an den Eingängen der ICs könnte die Performance verbessern. Eine solche Optimierung sollte insbesondere eine Verringerung der parasitären Kapazität und des Leckstroms beinhalten, während die ESD-Robustheit beibehalten wird. Mehrere ESD-Schutzstrukturen wurden auf ihre Eingangskapazität, ihren Leckstrom und die Robustheit gegen ESD analysiert. Die erste Schutzstruktur, die untersucht wurde, war eine Diode, die als einfachstes Schutzelement gilt. Des Weiteren wurden drei auf MOS-Transistoren basierende Schutzstrukturen, nämlich gate-grounded NMOS (GGNMOS), gate-coupled NMOS (GCNMOS) sowie substrate pump NMOS (SPNMOS) analysiert. Alle Schutzstrukturen basieren auf einem 180-nm-CMOS-Prozess. Die theoretischen Analysen der mit Cadence® simulierten Kapazitäten sowie die durch das Layout extrahierten Parasiten werden in Kombination mit TCAD Sentaurus®-Simulationen von Stromdichte und Temperatur für ausgewählte ESD-Schutzstrukturen vorgestellt.

Impact of electromagnetic interference on the functional safety of smart power devices for automotive applications

Integrated smart power devices gain more and more importance in the field of automotive systems. In addition to power transistors such devices usually contain several integrated diagnostic and protection functions. In the event of a fault these functions enable the connected control unit to react appropriately and to protect the application and thus the people. Smart power devices are often responsible for important tasks within a vehicle and are nowadays more and more used to substitute conventional elements like fuses, relays and switches. During the operation they are often exposed to harsh environmental conditions such as high operating temperatures, mechanical stress, etc. At the same time different electromagnetic interferences (EMI) may occur, which can affect their normal functionality. Especially in safety-critical applications such as the airbag control module or the Anti-lock Braking System their correct function is very important to avoid dangerous operating conditions and to ensure functional safety. Based on EMI investigations on a representative smart power high side switch it is shown in this paper to what degree of electromagnetic interference smart power devices are still able to correctly detect critical fault conditions and remain in their fail-save state.ZusammenfassungIm Bereich der Leistungselektronik werden in modernen Kraftfahrzeugen zunehmend so genannte ”Smart Power Devices“ eingesetzt. Sie beinhalten neben den Leistungstransistoren meist mehrere integrierte Diagnose- und Schutzfunktionen. Im Fehlerfall ermöglichen diese Funktionen dem angeschlossenen Steuergerät, entsprechend zu reagieren und die Anwendung und damit die Menschen zu schützen. Smart Power Devices sind oft für wichtige Aufgaben innerhalb eines Fahrzeugs verantwortlich und werden heutzutage immer häufiger eingesetzt, um herkömmliche Elemente wie Sicherungen, Relais und Schalter zu ersetzen. Während des Betriebs sind sie oft rauen Umgebungsbedingungen – wie hohen Betriebstemperaturen, mechanischen Belastungen usw. – ausgesetzt. Gleichzeitig können zusätzlich unterschiedliche elektromagnetische Störungen auftreten, welche die normale Funktionalität dieser Geräte beeinträchtigen können. Gerade in sicherheitskritischen Anwendungen wie dem Airbag-Steuermodul oder dem Antiblockiersystem ist ihre korrekte Funktion sehr wichtig, um gefährliche Betriebszustände zu vermeiden und die funktionale Sicherheit zu gewährleisten. Auf der Grundlage von Störfestigkeitsuntersuchungen an einem repräsentativen Smart Power High Side-Schalter wird in diesem Beitrag gezeigt, bis zu welchem Ausmaß an elektromagnetischen Störungen Smart Power Devices kritische Fehlerbedingungen immer noch korrekt erkennen können und somit die funktionale Sicherheit des Kraftfahrzeugs gewährleisten.

A system-on-chip NFC bicycle tire pressure measurement system

This paper presents a monolithically implemented NFC bicycle tire pressure measurement system (BTPMS) with integrated antenna, on-chip capacitive pressure and temperature sensor, RFID interface for HF/NFC and EEPROM. This NFC BTPMS has been designed using a 130 nm standard CMOS process and has an active chip area of 5.76 mm2. It provides significant cost advantages and impresses with its large scale integration. The used ISO 14443 RFID communication protocol ensures compatibility with state-of-the-art NFC devices. Configuration and calibration data are stored in the integrated EEP-ROM. This battery less stand-alone system is powered wirelessly by any state-of-the-art near field communication device. Using a two-point calibration technique, various measurements have been performed and analyzed regarding accuracy, sensitivity, reproducibility, and temperature dependency. In the pressure range of 1 bar to 6 bar and for temperatures between −15°C to 55°C a ±3σ accuracy of ±0.4 bar is achieved.