PROXIMITY AND AMBIENT LIGHT DETECTION

The Ambient Light Sensor sensitivity matches the response of the human eye. Both sensors achieve an impressive dynamic range performance.

CHALLENGE

Over the past 10 years SystematIC has designed a family of products which combines Ambient Light Sensing (ALS) and Infra-Red Proximity Sensing (PS) in a single SoC. The Ambient Light Sensor sensitivity matches the response of the human eye. The Proximity Sensor measures distance to an object using infra-red light reflection. For that the IC  is directly driving an external IR-LED. Our client is a leading global organization providing components to mobile phone manufacturing companies. The challenge for both the Ambient Light Sensor and the infra-red Proximity Sensor is to achieve a wide dynamic range. The key applications to be served by the ALS is backlighting control that adjusts display brightness of a mobile device to conserve battery energy. The key application to be served by the PS is to detect proximity of an object, in case of the mobile device application that is the human ear, for example to deactivate the touch screen. This makes the IC a perfect solution for touch-screen portable devices such as smart phones.

SOLUTION

The IC solution for the mobile devices has been perfected and improved over several generations of the product, taking into account the user feedback. In the latest version of the IC the on-chip Ambient Light Sensor achieves a very wide dynamic range, covering 1 millilux to 65 kilolux. The Proximity Sensor can measure up to 10 cm with a single LED pulse of 10 us and 50 mA. All measurements are accessible on an I2C communication bus. A programmable interrupt pin minimizes the need to poll the device for data, freeing up the microcontroller resources and reducing overall power consumption. The IC operates on supply voltages from 1.7 V to 3.6 V and consumes only 100 nA in standby mode and 100 uA in operating mode.

TIME

SystematIC has designed the full ASIC and reached tapeout in 3 months, and supported the ASIC development over several generations.

WE ARE PROUD

We developed a robust architecture with an impressive performance over the targetted temperature range of -40°C to +85°C. For that we successfully reduced and mitigated leakage currents effects at high temperature. In the proximity detection we succeeded to increase sensitivity by a factor of 64 compared to previous generations to improve dynamic range considerable. The proximity sensor readout features ambient-light suppression algorithms and is able to operate from dark rooms up to bright sun conditions. The product has independent photodiodes and readout circuits for the ALS and the PS on a single die.

SystematIC developed versatile but robust and temperature-resilient ambient-light and proximity sensor circuits that find application in smart phones or other devices using presence or short-distance detection.

BENEFITS FOR CUSTOMER

  • IP based readout, silicon-proven and mass-produced circuitry
  • IC product design and development support (incl. foundry cooperation) for several generations
  • Achieving a high-sensitivity Proximity Sensor readout allows IR-LED current reduction (factor of 64)
  • Customer optimization between power consumption (battery life) and Proximity Sensor performance (distance) in programmable application
  • Ambient-light cancellation algortithms enable optimal Proximity Sensor performance in wide range of ambient conditions, from natural sunlight to fluorescent and incandescent lamps
  • Proximity Sensor photodiode responsivity peak optimized at 850nm/950nm

KEY TECHNICAL STATISTICS

  • Chip Area: < 1 mm2
  • Supply Voltage: 1.7 V to 3.6 V
  • Proximity Range: 0 cm to 10 cm (up to 16-bit)
  • Ambient-Light Range: 1 mLux to 65 kLux
  • Temperature Range: -40 ⁰C to 85 ⁰C

OUR OTHER SUCCESS STORIES

IC solutions that are tailor made for you can help you achieve your business goals.

SystematIC was founded to help businesses envision, plan, and develop such custom IC solutions.

PROXIMITY AND AMBIENT LIGHT DETECTION

SystematIC has designed a family of products which combines Ambient Light Sensor (ALS) and Infra-red Proximity Detection Sensor (PS) in a single SoC. The ambient light sensor matches the response of the human eye. The infra red proximity sensor measures the distance to an object.  Our client is a leading global organization providing components to mobile phone manufacturing companies.

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CURRENT SENSOR

We were handed the responsibility of a current sensor IC that  monitors charge and discharge currents of a battery in a mobile phone and will remain insensitive to the variations of the supply voltage. We took charge of the entire design trajectory along with evaluation and redesign that was needed to make the final product a notch better than competition.

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TIRE PRESSURE MONITOR

In this project we developed an analog front-end architecture for a given capacitive MEMS pressure sensor. The front end must accurately measure the pressure in a tire and be robust against leakage, parasitics and noise. The SystematIC methodology was applied. First off, the sensor was electronically modelled to determine an optimal excitation and read out architecture. Next, during the detailed design phase the front-end was designed and layouted for a modern automotive IC application, including safety and test features.

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X-RAY DETECTOR READOUT

The customer has a leading international position in industrial X-ray crystallography systems. In one of these products a multi-channel HV passive X-ray sensor is applied for material analysis and an accurate matched channel readout and signal processing ASIC is required. SystematIC proposed an architecture of ultra-low noise front ends that are noise optimized to the sensor element and applied in a matched channel configuration. The digital electronics where designed as special CMOS CML logic to obtain low crosstalk.

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AC LED DRIVER IC

Our customer produces a range of AC LED modules for lamp manufacturers. The products were originally built with discrete components, a different set for each module type. For performance enhancement and simplification of production steps and supply chain, the customer was looking for a custom ASIC solution. The customer was also expecting improved performance on TRIAC dimmer compatibility and a reduction in product costs. With a programmable high-voltage ASIC and only a few external components (rectifier, fuse and surge) all module types can be made. LED modules with such an ASIC are directly driven from the AC mains voltage, are low-cost and are very compact and reliable. An electronic solution was created that made the customer AC LED lamp compatible with TRIAC dimmers. A discrete prototype was built and demonstrated to the customer just a few weeks after the first contact. The discrete electronics where chosen such that they could be implemented in a HV IC process.

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POINT-OF-LOAD POWER CONTROLLER

Our customer, a fabless semiconductor company, started a new product line of drivers and controllers for power converter applications in industrial applications. SystematIC took care of the design of a complex power controller IC targeting application in Point-of-Load Power Modules, used in Ethernet Routers and Switches and other Industrial Applications. The customer’s approach was to offer a very versatile IC to the market that also realized excellent performance parameters (efficiency, ripple, etc). The customer discovered a strong market interest and had marketing & sales and application support in place but lacked the IC design resources for a quick product development. Within a year SystematIC developed all accurate analog functions in a new IC process and delivered the verified mixed-signal chip design and layout.

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INTEGRATED POWER SWITCH

Applications supporting plug-and-play connections require (accurate) over-current protections, preferably implemented in a low-cost solid-state IC. For a division of a large semiconductor company the accurate current control was a design challenge that was tackled by involving SystematIC in the design. The area, cost-of-silicon and on-resistance of the integrated power switch are relevant parameters for the technology choice, but in any case dictate preference for an NMOS power switch. Using an NMOS switch however complicates the design of driver and sensing circuits. SystematIC did the challenging full-chip circuit design, including current sensing circuits using low-offset chopped amplifiers, adjustable over-current current control, over-temperature protection, and push-pull chargepumps to drive the NMOS.

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EAR PROTECTION CONTROL IC

Our customer DEC develops and produces Dynamic Sound technology products which can typically be used as stand-alone hearing protection or embedded in headphone systems, hearing aids and hearables. The IC we designed for DEC was an example of an integration project for SME and it covers most aspects of a SystematIC turnkey solution. Our contribution extends from system study to  implementation, manufacturability and testability for ears, from zeroing in the IC process to IC design and layout and the production preparation.

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ELECTRIC PROPULSION

State-of-the-art electric propulsion (EP) systems used in satellites may exhibit impressive performance, but the used technologies cannot be scaled down in size and power whilst retaining system performance. As a result, no conventional technologies for propulsion are available for the upcoming micro- and nanosatellite market. SystematIC partners in the HiperLoc-EP project which aims to use a novel electric propulsion approach and develop an Electrospray Colloid Electric Propulsion System (ECEPS) suitable for small (cubesat) form factors.

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