TOF Sensor Clock Replication for Stable Depth Phase Alignment
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Solution Overview
Problem
Existing time-of-flight (TOF) sensors face challenges in maintaining the accuracy of depth information due to variations in temperature, bias voltage, or manufacturing process, which affect the phase relationship between the transmission and sampling of light pulses.
Innovation Solution
The proposed solution involves a TOF sensor design that includes a clock signal generation circuit, a transmission circuit, a replicated transmission circuit, a delay locked loop, a clock tree, and a pixel array. This design ensures that the phase relationship between the transmission and sampling of light pulses is fixed at a preset value, maintaining accuracy despite environmental or process changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional TOF sensors are used without phase compensation circuits, then the device complexity is low, but the measurement precision degrades due to temperature, bias voltage, or process changes affecting the phase relationship between transmission and sampling clock signals
Solution Approach 1:
The patent applies the copying principle by creating a replicated transmission circuit that duplicates the transmission circuit's functionality. This replicated circuit generates a replicated clock signal that mirrors the transmission clock signal's characteristics. By copying the transmission circuit's behavior and applying it to the sampling path, the system compensates for phase shifts caused by environmental variations, thereby maintaining measurement precision without requiring complex external calibration systems
Solution Approach 2:
The patent implements feedback through a delay locked loop (DLL) that continuously monitors and adjusts the phase relationship between the transmission clock signal and the sampling clock signal. The DLL receives the replicated clock signal and generates control signals that adjust the sampling clock's phase to maintain a fixed predetermined phase difference. This closed-loop feedback mechanism automatically compensates for temperature, bias voltage, or process changes, ensuring consistent measurement accuracy
2Measurement precision
If a fixed predetermined phase difference is maintained between transmission and sampling clock signals, then the measurement precision is improved, but the device complexity increases due to additional compensation circuits
Solution Approach 1:
The patent uses copying by replicating the transmission circuit to generate a replicated clock signal that serves as a reference for the sampling operation. This replicated signal inherently contains the same phase characteristics as the transmission signal, and by using it to control the sampling clock, the system maintains a fixed predetermined phase difference without requiring complex external phase reference systems
Solution Approach 2:
The patent introduces an intermediary element - the delay locked loop (DLL) - that mediates between the transmission clock signal and the sampling clock signal. The DLL receives the replicated clock signal and generates control signals that adjust the sampling clock's phase. This intermediary component simplifies the overall system by providing a dedicated phase compensation mechanism that automatically maintains the required phase relationship
Data Source
AI summary
The present application discloses a time-of-flight (TOF) sensor and a related chip, electronic device, and distance measuring system. The TOF sensor includes: a clock signal generation circuit to generate a first clock signal and a second clock signal; a transmission circuit to generate a third clock signal based on the first clock signal, wherein the third clock signal is outputted to the light-emitting module; a replicated transmission circuit to simulate the transmission circuit, and generate a fourth clock signal based on the second clock signal; a delay locked loop to generate a fifth clock signal based on one of sixth clock signals and the fourth clock signal; a clock tree to generate the plurality of sixth clock signals based on the fifth clock signal; a pixel array, having pixel columns respectively sampling the reflected light pulse based on the plurality of sixth clock signals to generate a sampling result.