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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). The system should process multiple input signals in parallel, covering a voltage range of 0 V to 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

1. 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.

2. 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).

3. 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.

4. 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.

5. Evaluation and Optimization

   • Analyze the measurement results to identify sources of error.

   • Propose and implement 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: