Here is a reference design that leverages the fast GaN laser drivers to achieve a high-resolution and extended range in LIDAR vision.
With the increased popularity of LiDAR applications, the required specifications are constantly improving, especially for resolution and distance. A LiDAR system requires fast switching of high-current pulses to meet these performance specifications. This is where a gallium-nitride (GaN) power switch comes in. GaN is a wide-bandgap semiconductor that’s becoming the preferred solution for many high-power, high-speed switching applications.
For instance, an autonomous vehicle must be able to distinguish between other vehicles, buildings, road signs, pedestrians in dark clothing, etc., all while traveling at high speeds. For high-speed applications, the system must be able to detect an object with 10% reflectivity at a distance of 300 m and distinguish between objects 30 cm in size.
This specification translates into a design that requires 100 to 200 W of optical power and a repetition rate of up to 1 MHz to fill a front-facing field of vision (100° × 25° with a 0.1° resolution) and allow for a 20- to 60-Hz refresh rate.
This is a challenge for designers. Lasers transmitting in the near-infrared (IR) and visible regions can cause eye damage. With the popularity of near-infrared wavelength at around 905 nm, there is an eye safety energy limit of 250 nJ that must be met. If the range of power has to increase, and to increase the resolution the repetition frequency has to increase, the only way to maintain emission under the safety limit is to have extremely high energy pulses for an extremely short amount of time (and low duty cycle).
The requirement then comes to 100 W to 200 W for 1 ns to 2 ns at a 1-MHz to 2-MHz repetition rate.
GaN to the rescue
Texas Instruments offers a Nanosecond Laser Drive Reference Design for High-Resolution LIDAR that showcases the LMG1020, low side nanosecond (ns) GaN gate driver, which is capable of driving a FET to produce a 1 ns laser optical pulse in excess of 100W.
Click here for the reference design.
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