Laser Radar is a ranging technology that increasingly uses applications such as automobile advanced driving assistance systems (ADAS), gesture identification and 3D mapping. Especially in the automotive sector, with the trend of sensor fusion, Lidar combines image, ultrasonic, millimeters, mutual complement, to provide automobiles to provide a full-scale perception, to facilitate safer automatic driving. Ansian Semiconductor provides this full range of sensor programs and technology is far ahead, in single photon avalanche diode (SPAD) and silicon-optowal tube (SIPM) sensor technology is one of the market leaders, providing a complete Lidar program, including system, sensor, output And laser drive solutions.
ANANSIS Semiconductor Complete Lidar Plan
1 Lidar system has 6 main hardware function blocks: transmission, reception, beam steering, optical device, output, and power management. A typical LIDAR system block diagram is shown in Figure 1. Among them, Anshen American semiconductor provides SIPM / SPAD, laser driver reference design, power management, amplification and processing, and timing, histogram, point cloud generation and even system. Mature simulated SIPM products have C Series, J Series, R Series. The system has a SIPM array scanning the Lidar demo (more than 100 m scanning distance), fucking the SIPM with the image sensor, the latest 400 x 100 SPAD array PANDION.
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Figure 1: Typical LIDAR system block diagram
What is SPAD, SIPM and TOF
SPAD is a photodiode working in a Geiger Mode, just like photon trigger switches, in the "open" or "off" state. SIPM is composed of multiple separate SPAD sensors, each of which has its own quench resistance, so that a single SPAD cannot measure the lack of multiple photons at the same time. The flight time (TOF) refers to the time required to transmit a light pulse and then the sensor receives the time returned from the target. By light speed and TOF, the target distance can be calculated, the concept is simple, but it is subject to many challenges in the world, including harsh environments such as illumination conditions, low reflectivity targets and long distances. There are currently two TOF measurement techniques: single laser pulse method and multi-laser pulse method. Single laser pulse method refers to a high signal to noise ratio (SNR) each measured a single pulse returned. Multi-laser pulse method refers to a distance from a histogram data each time it is measured by histogram data. If the SNR can be improved, it can realize a further distance. TOF Lidar can be used in many applications such as robots, drones, industrial, mobile, automotive ADAS and automatic driving and enhanced real-world (AR) / virtual real-world (VR).
SIPM and SPAD are becoming an emerging LIDAR detector
SIPM and SPAD detects more than 200 m, 5% low reflectivity target, can also work in bright sunlight, excellent resolution, and as small aperture and solid state design to achieve compact systems into the car. And a cost advantage is a emerging LIDAR detector.
Car LIDAR sensor requirements
Strict consistency
Since the SIPM / SPAD works in the cover leather mode, it is difficult to control the consistency of the product. Ansian Semiconductor is currently the world's real-capacity vendors of SIPM products, and the voltage and gain provided by millions of sensors is very consistent, easy to calibrate and reduce manufacturing costs.
2. Equivalent to the car (IATF 16949, AEC Q102, -40 to 1050C operating temperature, in line with PPAP)
Anshen Mei Semiconductor has accumulated many years of professional experience in automobile production, with a very well-organized quality supervision and control system of the car, considering the automotive certification to design sensors and packages from the outset.
3. High photon detection rate (PDE) at 905 nm
The SIPM of the Ansian Semiconductor has today's best PDE, more than 12%, 30% in 2020.
4. High gain
The gain of the SIPM is 10,000 times the avalanche photodiode (APD), which is 1 million times of the PIN diode, crosstalk. 1881.20, provides excellent SNR.
SIPM array scanning Lidar system
The SIPM array scanning Lidar contains 16 905 NM laser diodes, one machine electrical rotary mirror for beam steering, Ansian Semiconductor's single-chip 1 x 16 SIPM array and processing electronic device, visiting angle (AOV) 80 ° X 5.53 °, pulse width 1 ns, system peak power 400 W, system size 22 cm x 18 cm x 13 cm. This system uses a 1D array to simultaneously sample multiple vertical points, and combined with horizontal uniaxial scanning, a complete image of the field of view can achieve real-time imaging of long-range low reflectivity targets.
FUSEONE system: Fusion image and Lidar
FuseOne combines 2 million pixel-level image sensors and SIPM-based flash Lidar, through software application fusion cameras and Lidar, obtains data distance, mobile rate, and other data, high sensitivity SIPM detector and phantom intelligence algorithm to achieve enhanced distance capability. FUSEONE is very cost-effective due to no mechanical radar scanning. The system uses 8 SIPM and 2 905 NM laser diodes, pulse width 20 ns, peak power 80 W, and receiver optical path employ 43 nm bandpass filter, Xilinx FPGA is used for edge processing full waveform acquisition, AOV is 25 ° X 3.6 °, under the light conditions of 20 kLUX outdoors, the pedestrian detected 45 m, and the car was detected by 85 m.
PANDION SPAD array to achieve long distance scanning Lidar
400 × 100 SPAD array has a CMOS logic device, array size 14 mm × 3 mm, pixel spacing 38.6 UM, using rolling shutter reading (100 channel parallel reading), passive quenching active reset (PQAR) characteristics can be obtained. 1881.5 NS recovery time, breakdown voltage of 3.3 V or more. Different from traditional point clouds, the PANDION SPAD LIDAR has formed an image.
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Figure 2: PANDION detects the target of different reflectance
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Figure 3: PANDION adopts an optical sub-counting intensity image
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Figure 4: Strength image of PANDion at a micro-light level
Summarize
SIPM and SPAD technology are key to receiver function in the Lidar system. Based on cover leather model avalanche principles, achieving compact, high gain sensors, Anshen Semiconductors are market leaders of these technologies, providing a complete Lidar program, including SIPM sensors, The SIPM array scans the Lidar system, fuses the FUSEONE system of SIPM flash Lidar and images, and the PANDION SPAD array, which has strong solid, cost-effective, in line with the advantages of car gauges, and actively develop innovation, while providing a wide range of on-site application support, related Application Note and Video Library, Product Demonstration System, Simulation Data of Terms of Models, etc., solve design challenges and promote innovation.
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