FPGA Readout for Frequency-Multiplexed Array of Micromechanical Resonators for Sub-Terahertz Imaging

Area of Science:

• Physics
• Electrical Engineering
• Materials Science

Background:

• Terahertz (THz) ray detection is crucial for various imaging and sensing applications.
• Microbolometer-based focal plane arrays (FPAs) utilizing microelectromechanical (MEMS) resonators are promising THz detector solutions.
• Designing high-performance, high-pixel-density sensors for THz detection presents significant challenges.

Purpose of the Study:

• To present a novel MEMS-resonator detector system fully managed by a Field Programmable Gate Array (FPGA).
• To demonstrate the FPGA's capability in controlling pixel excitation and tracking resonance frequency shifts caused by radiation.
• To enhance the open-loop readout technique for improved sensor performance.

Main Methods:

• Development of an innovative FPGA architecture featuring a lock-in matrix.
• Implementation of parallel digital lock-in amplifiers for precise resonance frequency tracking.
• Utilizing the FPGA for deterministic parallel processing, fast Analog-to-Digital Converter/Digital-to-Analog Converter (ADC/DAC) control, and high data throughput management.
• Measurements conducted on a frequency-multiplexed, 256-pixel sensor.

Main Results:

• The FPGA-managed MEMS-resonator detector successfully controlled pixel excitation and tracked radiation-induced frequency shifts.
• The novel FPGA architecture enhanced the open-loop readout technique by a factor of 32.
• The system demonstrated effective operation for imaging applications with a 256-pixel sensor.

Conclusions:

• FPGA technology is essential for advancing THz sensing, particularly for microbolometer-based FPAs.
• The presented FPGA architecture and parallel digital lock-in amplifier approach offer a significant improvement in THz detector performance.
• This work paves the way for high-performance, high-pixel-density THz imaging sensors.