Transimpedance Amplifier Current Limiting for Fast Overdrive Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Trans-impedance amplifiers (TIAs) in LIDAR systems take a long time to recover from being driven beyond their linear ranges, leading to blinding of detection channels and failure to detect additional reflections due to slow overdrive recovery.
Innovation Solution
A low-noise high-speed TIA with a current signal limiter is implemented, featuring a common-emitter input stage, a common-base output stage, a resistor between input and output terminals, and a current limiting circuit with a programmable current source and diode matrix to limit emitter current, ensuring the transistor operates within a linear region even under overdrive conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a TIA is designed with high gain to improve detection sensitivity, then detection precision is improved, but the TIA becomes easily overdriven by large transient current pulses, causing slow recovery and loss of detection capability
Solution Approach 1:
The patent introduces a current limiting circuit as an intermediary component between the APD and TIA. This circuit includes a current limiting transistor that acts as a mediator to restrict the maximum current reaching the TIA, preventing overdrive conditions while allowing the TIA to maintain its high gain configuration for sensitive detection of valid signals.
Solution Approach 2:
The patent dynamically changes the effective gain parameter of the detection system by introducing a current limiting mechanism. The current limiting circuit modifies the current parameter entering the TIA based on signal amplitude, effectively creating a variable gain system that maintains high sensitivity for weak signals while limiting the current for strong signals to prevent overdrive.
2Reliability
If the TIA linear range is expanded to accommodate large current pulses, then overdrive recovery is improved, but detection precision for weak signals deteriorates
Solution Approach 1:
The current limiting circuit serves as an intermediary that protects the TIA from large current pulses without requiring the TIA itself to have an expanded linear range. The limiting circuit intercepts and restricts excessive current before it reaches the TIA, allowing the TIA to maintain its optimized high-gain configuration for weak signal detection.
3Adaptability or versatility
If APD current gain is increased to improve detection range, then detection range is improved, but the TIA is more easily overdriven, causing detection channel blinding
Solution Approach 1:
The current limiting circuit acts as a protective intermediary between the high-gain APD and the TIA. It allows the APD to operate at high current gain levels to extend detection range, while simultaneously preventing the resulting large current pulses from overdriving the TIA and causing detection channel blinding.
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
Facilitates fast overdrive recovery, allowing for immediate detection of additional reflections by keeping transistors out of saturation regions, enhancing the performance of LIDAR systems in detecting transient current pulses.
Implementation Method 1
an avalanche photo-diode (APD) for sensing light to provide an input signal
Implementation Method 2
a current limiting circuit, the current limiting circuit includes a programmable current source coupled to the emitter terminal of the common-base configured transistor and a diode matrix coupled between the emitter terminal of the common-base configured transistor and the collector terminal of the common-emitter configured transistor. The diode matrix limits the emitter current
Data Source
AI summary
A high-speed low-noise trans-impedance amplifier (TIA) with fast overdrive recovery is suitable for use in light detection and ranging (LIDAR) receivers.