Steerable VCSEL Driver with Dynamic Voltage Control
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Solution Overview
Problem
Conventional laser drivers for VCSEL diode arrays face inefficiencies due to fixed supply voltage, leading to increased power consumption and decreased efficiency, and are ill-suited for applications like LIDAR that require driving multiple diodes with non-adjacent fields of view.
Innovation Solution
A steerable voltage-controlled laser driver with a steering circuit and current sensing circuit that selectively steers the laser drive signal to different VCSEL diodes with non-adjacent fields of view, maintaining a substantially constant current magnitude by adjusting the laser drive signal based on sensed voltage across a sense resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed supply voltage is used in the laser driver, then the circuit design is simplified, but the voltage drop across the current source transistor increases, leading to increased power consumption and decreased efficiency
Solution Approach 1:
The patent applies dynamics by replacing the fixed supply voltage with a dynamically adjustable voltage source that can be tuned based on operating conditions. The voltage controlled current source transistor adjusts its voltage drop dynamically to maintain saturation while minimizing power loss, resolving the contradiction between circuit simplicity and energy efficiency.
Solution Approach 2:
The patent changes the voltage parameter from fixed to variable, allowing the supply voltage to be adjusted according to the specific operating point and load conditions. This enables optimization of the voltage drop across the current source transistor to minimize power consumption while maintaining proper saturation operation.
2Device complexity
If a conventional laser driver is used for multiple VCSEL diodes, then the device structure is simple, but it cannot effectively drive diodes with non-adjacent fields of view, leading to photon cross-contamination
Solution Approach 1:
The patent applies segmentation by dividing the laser driver into multiple independent voltage controlled current source transistors, each dedicated to a specific VCSEL diode. This segmentation allows independent control of each diode's drive signal, enabling selective activation of non-adjacent diodes and preventing photon cross-contamination between adjacent fields of view.
Solution Approach 2:
The patent introduces voltage controlled switches as intermediaries between the drive signal and each VCSEL diode. These switches act as mediators that can selectively connect or disconnect each diode from the drive signal, enabling precise control over which diodes are active and preventing harmful photon cross-contamination.
3Reliability
If the voltage drop across the current source transistor is increased, then the transistor remains in saturation, but the power consumption increases and efficiency decreases
Solution Approach 1:
The patent changes the voltage parameter from fixed to variable, allowing the supply voltage to be adjusted according to the specific operating point and load conditions. This enables optimization of the voltage drop across the current source transistor to minimize power consumption while maintaining proper saturation operation.
Solution Approach 2:
The patent implements feedback control where the voltage controlled current source transistor adjusts its operation based on sensed conditions to maintain saturation. The feedback mechanism ensures the transistor remains in saturation while minimizing the voltage drop and associated power loss by dynamically optimizing the operating point.
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
This solution enhances efficiency by minimizing power consumption and enabling effective operation in applications like LIDAR by ensuring optimal voltage distribution across VCSEL diodes with non-adjacent fields of view, preventing photon cross-contamination and maintaining constant current.
Implementation Method 1
control circuitry configured to sense a magnitude of a current of the laser drive signal and to generate the feedback control signal based thereupon
Data Source
AI summary
An electronic device includes laser emitters, and a laser driver generating a laser drive signal for the laser emitters based upon a feedback control signal. A steering circuit selectively steers the laser drive signal to a different selected one of the plurality of laser emitters and prevents the laser drive signal from being steered to non-selected ones of the plurality of laser emitters, during each of a plurality of time periods. Control circuitry senses a magnitude of a current of the laser drive signal and generates the feedback control signal based thereupon. The feedback control signal is generated so as to cause the laser driver to generate the laser drive signal as having a current with a substantially constant magnitude.