Laser Receiving Circuit DC Bias Superposition ADC Dynamic Range
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Solution Overview
Problem
The existing laser receiving circuits in LiDAR systems face a decrease in signal-to-noise ratio due to an insufficient actual input dynamic range of the analog-to-digital converter, which affects the ranging performance.
Innovation Solution
A DC bias circuit is added to the laser receiving circuit to generate reverse DC voltage signals that are superimposed with the amplified voltage signals, effectively increasing the input dynamic range of the analog-to-digital converter and enhancing the signal-to-noise ratio by shifting the baseline of input voltage signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If AC coupling mode is used for ADC input port, then the circuit design is simple, but the actual input dynamic range is insufficient
Solution Approach 1:
The coupling function is segmented into two independent paths: AC coupling for the signal path and DC bias for the baseline path. This allows the AC coupling capacitor to handle only the AC signal while the DC bias circuit independently sets the baseline voltage, thereby expanding the effective input dynamic range without complicating the overall circuit design.
Solution Approach 2:
A DC bias circuit is introduced as an intermediary component that injects a controllable DC voltage into the ADC input. This intermediary element separates the DC baseline setting function from the AC signal coupling function, enabling the system to achieve both simple AC coupling design and expanded input dynamic range simultaneously.
2Reliability
If gain of amplifying circuit is increased, then signal-to-noise ratio improves, but input dynamic range requirement increases
Solution Approach 1:
The DC bias voltage is made dynamically adjustable to track and compensate for baseline drift caused by varying signal conditions. This dynamic adjustment allows the system to maintain optimal baseline positioning even when amplifying circuit gain changes, thereby improving signal-to-noise ratio without requiring a fixed increase in input dynamic range.
Solution Approach 2:
The baseline voltage parameter is changed dynamically through the DC bias circuit to adapt to different operating conditions. By adjusting the DC bias voltage parameter, the system can optimize the input dynamic range utilization for different signal levels, allowing higher amplifying circuit gain to be used effectively without exceeding the ADC's input range limitations.
Data Source
AI summary
The present application discloses a laser receiving circuit and a LiDAR. The laser receiving circuit includes an amplifying circuit, a DC bias circuit, and an analog-to-digital converter. The amplifying circuit is connected to the analog-to-digital converter and configured to amplify input first voltage signals to obtain second voltage signals, and the second voltage signals are AC voltage signals. The DC bias circuit is connected to the analog-to-digital converter and configured to generate reverse DC voltage signals, and the reverse DC voltage signals and the second voltage signals are superimposed to obtain third voltage signals. The analog-to-digital converter is configured to sample the third voltage signals.