This repository documents a lock-in amplifier prototype built for Advanced Instrumentation work. Version 1 explored an analogue front end, switch-based phase-sensitive detection, and STM32 NUCLEO data acquisition. The first prototype was useful as a learning platform, and board is currently under re-design to hit some missed-target requirements.
The v1 architecture used:
- a pre-amplifier and bandpass front end for the measured AC signal
- microcontroller-generated sine and cosine pulse references
- switch-based I/Q phase-sensitive detector stages
- analogue low-pass filtering and STM32 ADC readout
- serial transfer to a PC for inspection and readout
The prototype confirmed the broad signal path and highlighted practical issues to address in v2, especially around robustness, signal conditioning, filtering choices, and implementation complexity.
| Reference | Description |
|---|---|
LIA_SPICE_SIM/ |
LTspice schematic sources for analogue circuit exploration |
Sim_LIA_V1.asc, Simulation_LIA.asc |
Root-level LTspice schematic files from early v1 work |
LIA_IMG/LIA_System_Mod.png |
System-level architecture diagram |
LIA_IMG/LIA_Flowchart.png |
Signal-flow and subsystem diagram |
LIA_IMG/LIA_PCB.jpg |
Assembled v1 PCB photo |
LIA_IMG/LIA_block.png |
Early concept block diagram |
Version 2 should use the v1 results as design input rather than treating v1 as a finished platform. The immediate goal is to keep the repository clean enough to support that redesign: circuit references remain available, but the project history is not buried under generated files or incomplete prototype code.