Variable-Gain Transimpedance Amplifier With Constant Bandwidth
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Solution Overview
Problem
Fixed gain trans-impedance amplifiers in interferometric fiber-optic gyro systems suffer from degraded gyro bias performance due to radiation exposure and optical losses over time, requiring costly calibration and stockholding of multiple parts, while variable gain approaches adversely affect amplifier bandwidth.
Innovation Solution
A variable gain trans-impedance amplifier system with a control device using a capacitor, resistors, and a field effect transistor switch, activated by an integrator or digital signal from the fiber-optic gyro system, to adjust gain in response to changing input conditions, maintaining bandwidth and compensating for radiation and aging-related losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed gain trans-impedance amplifier is used, then calibration is simple and stable, but gyro bias performance degrades due to radiation and aging
Solution Approach 1:
The patent implements a variable gain trans-impedance amplifier that dynamically adjusts its gain based on detected signal levels. The amplifier transitions from a fixed gain design to a dynamic gain control system that responds to radiation-induced fiber darkening and aging-related optical losses, thereby maintaining reliable gyro bias performance under varying environmental conditions.
Solution Approach 2:
The patent employs a feedback mechanism where the amplifier monitors its own output and automatically adjusts gain to maintain optimal performance. This closed-loop control compensates for radiation exposure effects and optical fiber degradation over time, preventing the performance degradation that occurs with fixed gain amplifiers.
2Reliability
If variable gain amplifier is used to compensate for losses, then gyro bias performance is maintained, but amplifier bandwidth degrades
Solution Approach 1:
The patent implements a variable gain trans-impedance amplifier that dynamically adjusts its gain based on detected signal levels. The amplifier transitions from a fixed gain design to a dynamic gain control system that responds to radiation-induced fiber darkening and aging-related optical losses, thereby maintaining reliable gyro bias performance under varying environmental conditions.
Solution Approach 2:
The patent changes the gain parameter of the amplifier dynamically while maintaining bandwidth characteristics. By adjusting only the gain parameter in response to signal level changes, the system compensates for losses without significantly degrading the amplifier bandwidth, thus resolving the contradiction between maintaining performance and preserving speed.
3Manufacturing precision
If fixed gain amplifier is calibrated for maximum voltage output, then initial performance is optimized, but performance degrades over time due to optical losses
Solution Approach 1:
The patent performs initial calibration to establish a baseline gain setting, then implements automatic gain adjustment mechanisms that activate when signal levels deviate from the calibrated range. This preliminary calibration combined with ongoing automatic adjustment ensures both initial optimization and long-term reliability.
Solution Approach 2:
The patent employs a feedback mechanism where the amplifier monitors its own output and automatically adjusts gain to maintain optimal performance. This closed-loop control compensates for radiation exposure effects and optical fiber degradation over time, preventing the performance degradation that occurs with fixed gain amplifiers.
4Reliability
If multiple calibration parts are stocked for different conditions, then performance under various conditions is maintained, but cost and complexity increase
Solution Approach 1:
The patent implements a universal amplifier design with automatic gain control that can adapt to multiple operating conditions (radiation exposure, aging, temperature variations) without requiring different calibration parts. This single multi-functional amplifier replaces the need for stocking multiple specialized components.
Solution Approach 2:
The patent enables the amplifier to automatically detect and compensate for its own performance degradation due to radiation and aging. The self-adjusting gain mechanism eliminates the need for external calibration interventions and multiple calibration parts, allowing the system to maintain performance autonomously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The variable gain amplifier effectively mitigates the effects of radiation and aging on gyro bias performance without significantly degrading amplifier bandwidth, providing consistent output and reducing the need for frequent calibration and part inventory.
Implementation Method 1
a switch connected between the third resistor and a biased voltage, and a controller that controls the switch based on the output of the amplifier. In another aspect of the invention, the switch is a field effect transistor and the controller is an integrator
Implementation Method 2
the controller is an integrator
Data Source
AI summary
A trans-impedance amplifier with gain control for a fiber optic rotation rate sensor. A variable gain amplifier having gain control based on keeping the amplifier output above a certain level. The gain control approach allows the amplifier bandwidth to remain constant. A gain control circuit includes a control device connected to ground and the amplifier feedback network. The input to the gain control circuit may be the amplifier output that has been filtered, or the input could be from an external circuit or microcontroller.