FMCW LiDAR Frequency-Domain AGC for Dynamic Range Control
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Solution Overview
Problem
FMCW LIDAR systems face challenges in dynamic range limitations, leading to signal distortion and noise interference due to high or low intensity signals, which are not effectively addressed by current technologies, resulting in increased power consumption, component size, and cost.
Innovation Solution
The implementation of automatic gain control (AGC) across optical, analog, and digital paths in FMCW LIDAR systems, which adjusts the dynamic range by applying variable gain to reduce signal distortion and noise interference, allowing for efficient processing within a smaller dynamic range without increasing power, area, or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bits are added to ADCs and digital datapaths to increase dynamic range, then dynamic range is improved, but power consumption, area, and cost increase
Solution Approach 1:
The patent implements dynamic range adjustment by selectively enabling or disabling specific bits in the ADC and digital datapath based on the actual signal dynamic range requirements. This dynamic configuration allows the system to adapt the number of active bits to match the actual signal needs, rather than permanently allocating maximum bits for all operating conditions.
Solution Approach 2:
The system changes the effective resolution parameter of the ADC and digital processing path by adjusting which bits are active. The patent dynamically modifies the bit allocation parameter based on measured signal characteristics, enabling the system to operate with fewer bits when signal dynamic range is low, thereby reducing power consumption while maintaining adequate measurement precision.
2Measurement precision
If bits are added to ADCs and digital datapaths to increase dynamic range, then dynamic range is improved, but device area and cost increase
Solution Approach 1:
The patent implements dynamic range adjustment by selectively enabling or disabling specific bits in the ADC and digital datapath based on the actual signal dynamic range requirements. This dynamic configuration allows the system to adapt the number of active bits to match the actual signal needs, rather than permanently allocating maximum bits for all operating conditions.
Solution Approach 2:
The system changes the effective resolution parameter of the ADC and digital processing path by adjusting which bits are active. The patent dynamically modifies the bit allocation parameter based on measured signal characteristics, enabling the system to operate with fewer bits when signal dynamic range is low, thereby reducing power consumption while maintaining adequate measurement precision.
3Device complexity
If optical or analog components are used, then system complexity is reduced, but dynamic range is limited by component minimum requirements
Solution Approach 1:
The patent introduces digital signal processing as an intermediary between the optical/analog front end and the final measurement output. By placing digital processing stages after the ADC, the system can extend the effective dynamic range through digital techniques without requiring the optical and analog components to inherently support the full dynamic range, thus resolving the contradiction between component simplicity and measurement precision.
Solution Approach 2:
The patent replaces the need for high-dynamic-range optical and analog components with digital processing capabilities. Instead of relying on complex optical attenuators or high-range analog amplifiers, the system uses digital signal processing to extend dynamic range, substituting mechanical/optical complexity with computational methods.
Data Source
AI summary
A light detection and ranging (LIDAR) system includes an automatic gain control (AGC) unit to reduce the dynamic range, reducing processing power and saving circuit area and cost. The system detects a return beam of a light signal transmitted to a target, having a first dynamic range in a time domain. An analog to digital converter (ADC) generates a digital signal based on the return beam. A processor can perform time domain processing on the digital signal, convert the digital signal from the time domain to a frequency domain, and perform frequency domain processing on the digital signal in the frequency domain. The AGC unit can measure a power of the return beam, and apply variable gain in the frequency domain to reduce a dynamic range of the return beam to a second dynamic range lower than the first dynamic range.