Project B1 - Sensor Noise Performance and Analogue System Design

This project focusses on low-noise analogue signal processing and signal conditioning for maximizing the signal-to-noise ratio for the various magnetic field sensors that are being researched in the CRC. It therefore provides the essential link between sensor devices (project area A) and subsequent digital signal processing (project B2). It also plays an important role in measurement system design, which is required for implementing the sensors on applications in biomagnetic diagnostics.

Thorough noise analysis for the various realizations of magnetoelectric and ΔE-effect sensors is a major area of work in order to conceive and build low-noise analogue front ends for signal acquisition. Therefore, all involved noise sources have to be investigated and appropriate descriptions, i.e. noise models, have to be developed. Generally, all noise sources can be categorized into sensor-intrinsic noise sources and noise of the readout electronics. In the interest of a minimum limit of detection, it is always required that the sensor itself contributes predominantly to the overall system noise. The noise of the sensor is therefore of particular research interest. However, to be able to characterize the sensor noise appropriately, and thus gain further insight into the underlying mechanisms, the electronics need to be designed very carefully. In particular, it is necessary to be able to quantify the noise of the measurement electronics and minimize its influence as far as possible. Research has shown that the noise behavior of the sensors is constantly improving, which in turn requires continuous adaptation of the electronics. In fact, the entire process of noise measurements, noise modeling, and adjustments of the sensor electronics can be understood as an iterative process which needs to be performed for every type of sensor system and change in sensor design. The process described has already been performed for various types of sensor systems and will be expanded to include recently developed sensor concepts within the CRC, e.g. electrical frequency conversion with inductive readout.

In addition to well-established sensor concepts, novel readout methods will be investigated. Instead of utilizing piezoelectric materials for the conversion of a mechanical deflection into an electrical voltage, microwave resonators at approximately 3 GHz have proven to be suitable for the readout of magnetoelectric sensors. Also effect modulation concepts, e.g. based on flux modulation, promise to increase the signal-to-noise ratio (SNR). As a result, for each individual sensor concept the most suitable readout system with the highest possible SNR will be determined and the quantity limiting the performance will be known based on the developed noise models.

Based on noise investigations and readout system development, macroscopic setups emerge. To that end, highly optimized application-specific integrated circuits (ASICs) will be designed for those sensor types and applications, where off-the-shelf components are limiting the performance of the system. ASICs are electronics that are customized for a specific sensor type. In contrast, commercial off-the-shelf electronic circuits are rather aiming for a broader range of specifications and applications. As a result, in integrated circuit design the very specific requirements of the sensor can be taken into account. The electronics can be optimized for very specific requirements and thus the overall performance can be improved. Specific ASIC designs will include integrated electronics for ΔE-effect surface acoustic wave (SAW) sensors in the megahertz range as well as ultralow-noise amplifiers for the low frequency range (kHz).

Involved Researchers

Person		Role
	Prof. Dr.-Ing. Michael Höft Electrical Engineering Microwave Group	Project lead
	Prof. Dr. Andreas Bahr Electrical Engineering Sensor System Electronics	Project lead
	M.Sc. Johan Arbustini Electrical Engineering Sensor System Electronics	Doctoral researcher
	M.Sc. Henrik Wolframm Electrical Engineering Microwave Group	Doctoral researcher

Role within the Collaborative Research Centre

As can be deduced from the working program, this project provides analogue signal processing and conditioning as the sole project. It complements the hardware of the various kinds of thin-film magnetic field sensors under investigation with the required electronic circuits in order to facilitate their practical application. It therefore provides the indispensable link between bare sensor hardware and subsequent digital signal processing. It also deals with an important part in measurement system design, required for bringing the sensors to application in biomagnetic diagnostics. In particular, the following collaborations with other projects are planned:

Project-related Publications

H. Wolframm, J. Hoffmann, R. Burgardt, E. Elzenheimer, G. Schmidt, M. Höft: PCB Coil Enables In Situ Calibration of Magnetoelectric Sensor Systems, Current Directions in Biomedical Engineering, vol. 9, no. 1, 567-570, 2023.

P. Durdaut, M. Höft: Performance Analysis of Resonantly Driven Piezoelectric Sensors Operating in Amplitude Mode and Phase Mode, Sensors, 23(4), 1899, 2023.

J. Muñoz, J. Arbustini, E. Elzenheimer, M. Höft, A. Bahr: Digital Approaches on Frequency Tuning for Magnetoelectric Sensors, ICECS, 29th IEEE International Conference on Electronics, Circuits & Systems, Glasgow, Scotland, 2022.

H. Wang, J. Arbustini, E. Elzenheimer, V. Schell, M. Höft, E. Quandt, G. Schmidt, H. Heidari, A. Bahr: Study of Chopping Magnetic Flux Modulation on Surface Acoustic Wave Magnetic Sensor, ICECS, 29th IEEE International Conference on Electronics, Circuits & Systems, Glasgow, Scotland, 2022.

J. Arbustini, J. Muñoz, H. Wang, E. Elzenheimer, J. Hoffmann, L. Thormählen, P. Hayes, F. Niekiel, H. Heidari, M. Höft, E. Quandt, G. Schmidt, A. Bahr: MEMS Magnetic Field Source for Frequency Conversion Approaches for ME Sensors, BMT2022 , Joint Annual Conference of the Austrian, German and Swiss Societies for Biomedical Engineering, 2022.

E. Elzenheimer, C. Bald, E. Engelhardt, J. Hoffmann, P. Hayes, J. Arbustini, A. Bahr, E. Quandt, M. Höft, G. Schmidt: Quantitative Evaluation for Magnetoelectric Sensor Systems in Biomagnetic Diagnostics, MDPI Sensors, vol. 22, no. 3, 1018, 2022.

C. Müller, P. Durdaut, R. B. Holländer, A. Kittmann, V. Schell, D. Meyners, M. Höft, E. Quandt, J. McCord: Imaging of Love Waves and Their Interaction with Magnetic Domain Walls in Magnetoelectric Magnetic Field Sensors, Advanced Electronic Materials, 2200033, 2022.

B. Spetzler, P. Wiegand, P. Durdaut, M. Höft, A. Bahr, R. Rieger, F. Faupel: Modeling and Parallel Operation of Exchange-Biased Delta-E Effect Magnetometers for Sensor Arrays, MDPI Sensors, vol. 21, no. 22, 759, 2021.

P. Durdaut, C. Müller, A. Kittmann, V. Schell, A. Bahr, E. Quandt, R. Knöchel, M. Höft, J. McCord: Phase Noise of SAW Delay Line Magnetic Field Sensors, Sensors, vol. 21, issue 16, 5631, 2021.

B. Spetzler, C. Bald, P. Durdaut, J. Reermann, C. Kirchhof, A. Teplyuk, D. Meyners, E. Quandt, M. Höft, G. Schmidt, F. Faupel: Exchange Biased Delta-E Effect Enables the Detection of Low Frequency pT Magnetic Fields with Simultaneous Localization, Scientific Reports 11, Article no. 5269, 2021.

P. Durdaut, E. Rubiola, J.-M. Friedt, C. Müller, B. Spetzler, C. Kirchhof, D. Meyners, E. Quandt, F. Faupel, J. McCord, R. Knöchel, M. Höft: Fundamental Noise Limits and Sensitivity of Piezoelectrically Driven Magnetoelastic Cantilevers, Journal of Microelectromechanical Systems, vol. 29, issue 5, 2020.

B. Spetzler, C. Kirchhof, J. Reermann, P. Durdaut, M. Höft, G. Schmidt, E. Quandt, F. Faupel: Influence of the Quality Factor on the Signal to Noise Ratio of Magnetoelectric Sensors Based on the Delta-E Effect, Applied Physics Letters, vol. 114, issue 18, 183504, 2019.

P. Durdaut, A. Kittmann, A. Bahr, E. Quandt, R. Knöchel, M. Höft: Oscillator Phase Noise Suppression in Surface Acoustic Wave Sensor Systems, IEEE Sensors Journal, vol. 18, no. 12, pp. 4975-4980, 2018.

S. Salzer, V. Röbisch, M. Klug, P. Durdaut, J. McCord, D. Meyners, J. Reermann, M. Höft, R. Knöchel: Noise Limits in Thin-Film Magnetoelectric Sensors With Magnetic Frequency Conversion, IEEE Sensors Journal, vol. 18, no. 2, pp. 596-604, 2018.

A. Kittmann, P. Durdaut, S. Zabel, J. Reermann, J. Schmalz, B. Spetzler, D. Meyners, N. X. Sun, J. McCord, M. Gerken, G. Schmidt, M. Höft, R. Knöchel, F. Faupel, E. Quandt: Wide Band Low Noise Love Wave Magnetic Field Sensor System, Scientific Reports, vol. 8, no. 278, 2018.

P. Durdaut, J. Reermann, S. Zabel, C. Kirchhof, E. Quandt, F. Faupel, G. Schmidt, R. Knöchel, M. Höft: Modeling and Analysis of Noise Sources for Thin-Film Magnetoelectric Sensors Based on the Delta-E Effect, IEEE Transactions on Instrumentation and Measurement, vol. 66, no. 10, pp. 2771-2779, 2017.

P. Durdaut, V. Penner, C. Kirchhof, E. Quandt, R. Knöchel, M. Höft: Noise of a JFET Charge Amplifier for Piezoelectric Sensors, IEEE Sensors Journal, vol. 17, no. 22, pp. 7364-7371 , 2017.

J. Reermann, C. Bald, P. Durdaut, A.Piorra, D. Meyners, E. Quandt, M. Höft, G. Schmidt: Adaptive Mehrkanalige Geräuschkompensation für Magnetoelektrische Sensoren, Proc. DAGA, Kiel, Germany, 2017.

P. Durdaut, S. Salzer, J. Reermann, V. Röbisch, J. McCord, D. Meyners, E. Quandt, G. Schmidt, R. Knöchel, M. Höft: Improved Magnetic Frequency Conversion Approach for Magnetoelectric Sensors, IEEE Sensors Letters, vol. 1, no. 3 , 2017.

P. Durdaut, S. Salzer, J. Reermann, V. Röbisch, P. Hayes, A. Piorra, D. Meyners, E. Quandt, G. Schmidt, R. Knöchel, M. Höft: Thermal-Mechanical Noise in Resonant Thin-Film Magnetoelectric Sensors, IEEE Sensors Journal, vol. 17, no. 8, pp. 2338-2348, 2017.

S. Salzer, P. Durdaut, V. Röbisch, D. Meyners, E. Quandt, M. Höft, R. Knöche: Generalised Magnetic Frequency Conversion for Thin Film Laminate Magnetoelectric Sensors, EEE Sensors Journal, vol. 17, no. 5, pp. 1373-1383, 2017.

J. Reermann, C. Bald, S. Salzer, P. Durdaut, A. Piorra, D. Meyners, E. Quandt, M. Höft, Gerhard Schmidt: Comparison of Reference Sensors for Noise Cancellation of Magnetoelectric Sensors, IEEE Sensors, Orlando, 2016.

E. Yarar, S. Salzer, V. Hrkac, A. Piorra, M. Höft, R. Knöchel, L. Kienle, E. Quandt: Inverse Bilayer Magnetoelectric Thin Film Sensor, Applied Physics Letters, vol. 109, issue 2, 2016.