PA - Multichannel analog lock-in amplifier for EIT

Mehrkanaliger analoger Lock-in-Verstärker für EIT

Multichannel analog lock-in amplifier for EIT

Objective

The goal of this work is to design, implement, and evaluate a multichannel analog lock-in amplifier system for Electrical Impedance Tomography (EIT) and to evaluate the feasibility of using such a design in a high channel count EIT system. The lock-in amplifier system should process multiple input signals in parallel (minimum of 4, better 16), covering a voltage range of +-5 V and operating at frequencies from 1 kHz to 100 kHz. The signal amplitudes of the inputs will be in a range of 1mV to 100mV and have a SNR of around 20dB. The system's accuracy must achieve an amplitude error of less than 1% and a phase error of less than 5° for all channels over the complete specified range of operation.

Tasks

Literature Review and Theoretical Background

• Research the principles of lock-in amplifiers, focusing on their application in EIT.

• Study the challenges of multichannel signal processing and the design considerations for analog circuits.

• Identify the performance in terms of measurement error of existing analog lock-in amplifiers.

System Design

• Develop a circuit design for multiple lock-in amplifiers capable of processing signals in the specified range.

• Select appropriate components (e.g., operational amplifiers, filters, mixers, etc.) to meet the accuracy and frequency requirements.

• Simulate and evaluate the system design via simulations tools (e.g. LTSpice).

PCB Design and Implementation

• Create a schematic and PCB layout using CAD software (e.g., Altium Designer, KiCAD).

• Fabricate the PCB and assemble the components.

Integration and Testing

• Interface the PCB with suitable lab equipment for input signal generation and output evaluation (e.g., function generators, oscilloscopes).

• Verify the system's performance in terms of amplitude and phase accuracy.

Calibration

• Identify and perform the necessary measurements needed to calibrate for the measurement errors.

• Implement a calibration algorithm.

• Analyze the measurement error with calibration.

Evaluation and Optimization

• Analyze the measurement results to identify sources of error.

• Propose improvements to the design if necessary to meet the error thresholds.

• Evaluate the feasibility of using parallel analog lock-in amplifiers for a 256 channel EIT system

Zeitplanung:

Checklist

• Introduction / tour in M4

• Urheberrechtsvereinbarung signed: https://www.tuhh.de/t3resources/sls/pdf/ZPA/Formulare_oeffentlich/Rechte_an_Abschlussarbeiten.pdf

• if applicable: signed confidential agreement

• official registration

Helpful links:

• Thesis Work / Studentische Arbeiten 

• Criteria for the evaluation of Bachelor's and Master's theses, handout version

• Laborordnung

• Spotlights / Kurzvorträge

• Templates (Latex, ppt etc.)

Document Upload Final Thesis / Dokumentenabgabe Abschlussdokument

File of final presentation / Dokumentenabgabe Abschlusspräsentation

Link for further files / Link für weitere Dokumente