FMCW LiDAR Time-Domain AGC for Wide Dynamic Range Signals
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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 increasing bits in ADCs and digital datapaths, as this increases power, area, and cost without ensuring improved dynamic range.
Innovation Solution
The implementation of automatic gain control (AGC) across optical, analog, or digital paths in LIDAR systems, which adjusts the dynamic range by applying variable gain to reduce signal distortion and noise interference, allowing for reliable processing of signals within a specified range without increasing power, area, or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bits in ADCs and digital datapaths are increased to improve dynamic range, then dynamic range is improved, but power consumption increases
Solution Approach 1:
The patent applies dynamic gain adjustment in the digital signal processing path, where the gain value is varied based on the detected signal intensity. This allows the system to adaptively optimize the signal level for the ADC input, improving dynamic range without requiring a fixed high-bit-depth ADC throughout the entire system.
Solution Approach 2:
The patent changes the gain parameter in the digital datapath to optimize signal levels. By adjusting the gain parameter dynamically based on signal conditions, the system achieves improved dynamic range performance without increasing ADC bit depth, thereby avoiding the associated power consumption increase.
2Measurement precision
If bits in ADCs and digital datapaths are increased to improve dynamic range, then dynamic range is improved, but device area increases
Solution Approach 1:
The patent uses dynamic gain control in the digital path to effectively increase dynamic range without requiring additional physical resources. By adjusting the gain parameter software-controlled, the system achieves higher dynamic range performance using the same hardware footprint, avoiding area increase.
Solution Approach 2:
The patent modifies the gain parameter in the digital signal processing chain to optimize dynamic range. This parameter-based solution achieves improved performance without adding physical components or increasing device area, as it utilizes existing digital processing resources more effectively.
3Measurement precision
If bits in ADCs and digital datapaths are increased to improve dynamic range, then dynamic range is improved, but manufacturing cost increases
Solution Approach 1:
The patent implements dynamic gain adjustment in the digital path, which can be achieved through software or firmware control of existing digital signal processing components. This approach improves dynamic range without requiring more expensive high-bit-depth ADCs or additional hardware, thereby reducing manufacturing cost.
Solution Approach 2:
The patent optimizes dynamic range by adjusting the gain parameter in the digital datapath rather than increasing ADC bit depth. This parameter-based solution uses existing hardware more effectively, avoiding the need for more expensive components and reducing overall manufacturing cost.
4Ease of operation
If optical or analog components are used, then signal processing is enabled, but dynamic range is limited
Solution Approach 1:
The patent introduces a digital gain control stage as an intermediary between the ADC and subsequent digital signal processing components. This digital gain stage acts as a mediator that can flexibly adjust signal levels without the physical limitations of optical or analog gain control, thereby extending the effective dynamic range while maintaining signal processing capability.
Solution Approach 2:
The patent replaces analog or optical gain control mechanisms with digital gain control in the signal processing path. This substitution eliminates the dynamic range limitations inherent in analog components while maintaining full signal processing capability, as digital processing can achieve precise gain adjustment without physical constraints.
Data Source
AI summary
A frequency modulated continuous wave (FMCW) light detection and ranging (LIDAR) system includes an automatic gain control (AGC) unit to reduce the dynamic range of the signal to be processed. The system detects a return beam of a light signal transmitted to a target, having a first dynamic range in a time domain. The AGC unit can measure a power of the return beam, and apply variable gain in the time domain to reduce a dynamic range of the return beam to a lower dynamic. 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.