Enhanced bandwidth, high gain, low noise transimpedance amplifier for asynchronous optical sampling systems

Area of Science:

• Electronics
• Terahertz Technology
• Signal Processing

Background:

• Identifying high-bandwidth, low-noise amplification devices is crucial for terahertz (THz) antenna and photodiode signal processing.
• Minimizing amplifier input capacitance is essential for achieving the lowest noise levels in sensitive detection circuitry.
• Careful integration of amplifier and detection circuits is required to reduce parasitic capacitance and enhance performance.

Purpose of the Study:

• To detail a methodology for selecting optimal low-noise, high-bandwidth amplification devices for THz applications.
• To demonstrate a technique for minimizing feedback parasitic capacitance in amplifier design.
• To present a transimpedance amplifier (TIA) optimized for low-noise THz signal detection.

Main Methods:

• Detailed methodology for identifying high-bandwidth, low-noise voltage-amplification devices.
• Development and validation of a technique to minimize feedback parasitic capacitance.
• Implementation of a transimpedance amplifier (TIA) with specific gain, bandwidth, and SNR characteristics.

Main Results:

• A transimpedance amplifier (TIA) was demonstrated with 100 MΩ gain, 0.5 MHz bandwidth, and 23 dB SNR for a 5 nA input.
• The TIA, when integrated into a 1550 nm fiber-based THz asynchronous optical sampling system, achieved a 700 mV signal with 26 dB SNR from an 8 nA source.
• Real-time, sub-second THz data collection with 30 dB SNR was achieved by averaging 16 scans, eliminating the need for a separate data acquisition trigger.

Conclusions:

• Minimizing amplifier input capacitance through careful circuit integration is key to achieving low-noise amplification in THz systems.
• The developed TIA design significantly improves SNR and enables efficient, trigger-less THz data acquisition.
• This approach facilitates real-time, high-sensitivity THz measurements, advancing applications in spectroscopy and imaging.