High-performance fully differential photodiode amplifier for miniature fiber-optic gyroscopes

Area of Science:

• Optoelectronics
• Instrumentation and Measurement
• Optical Engineering

Background:

• Electrical cross coupling is a significant challenge in miniature fiber-optic gyroscopes (FOGs), leading to critical dead band errors.
• Conventional instrumentation amplifiers struggle to meet the bandwidth demands of miniature FOGs due to photodiode and parasitic capacitances.

Purpose of the Study:

• To develop a high-performance, fully differential photodiode amplifier to overcome bandwidth limitations and suppress interference in FOGs.
• To demonstrate the effectiveness of the proposed amplifier in reducing errors and improving the performance of miniature FOGs.

Main Methods:

• Implemented a fully differential photodiode amplifier design.
• Utilized reverse bias on the photodiode to mitigate bandwidth limitations.
• Replaced the feedback resistor with a modified tee-network and incorporated a DC cancellation loop.

Main Results:

• Achieved a fully differential photodiode amplifier with 880 kΩ gain and 3.5 MHz bandwidth for a 300 m fiber coil FOG.
• Demonstrated significant reduction in angular random walk and bias drift in the experimental FOG.
• Eliminated the ~1°/h dead band error observed with a PINFET receiver.

Conclusions:

• The proposed fully differential photodiode amplifier effectively suppresses electrical cross coupling and eliminates dead band errors in FOGs.
• This amplifier design enhances FOG performance by reducing noise and improving bias stability.
• The developed amplifier meets the stringent bandwidth requirements for high-performance miniature FOG applications.