High speed CMOS image sensors Wim Wuyts Sr. Staff Applications Engineer Cypress Semiconductor Corporation Belgium Vision 2006

Transcription

1 High speed CMOS image sensors Wim Wuyts Sr. Staff Applications Engineer Cypress Semiconductor Corporation Belgium Vision 2006 P E R F O R M

2 Outline Introduction Architecture Analog high speed CIS Digital high speed CIS 6T snapshot pixel type Applications Holographic data storage Line sensors Standard high speed products: LUPA-family Conclusion 2 High speed CMOS image sensors Vision 2006

3 Why? Why high speed? High speed motion/data analysis for various application fields e.g. military ballistics 3 High speed CMOS image sensors Vision 2006

4 Introduction Cypress has huge experience in high-speed CMOS Image Sensor (CIS) design (almost) All big players works with us Current max. pixel throughput of 13.2 Gpixels/s Typical with multiple parallel analog output tabs Now high-speed ADCs, LVDS output and on-chip timing sequencer available Both array and linear sensors Typical applications: high-speed motion analysis (crash and impact test), holographic data storage, digital film slow motion capture 4 High speed CMOS image sensors Vision 2006

5 Introduction What s high speed? Typically > 100 MPixels/s Requirements for high speed sensor design: High speed read out architecture (> 50 MPixels / internal tab) High sensitive snapshot shutter pixel with low Parasitic Light Sensitivity (PLS) High speed ADCs High speed interface (LVDS) 5 High speed CMOS image sensors Vision 2006

6 Technology: architecture High-speed read out architecture: 60+ MPixels/s / internal analog tab Parallel analog outputs e.g. 128*60 Mhz = 7.68 Gpixels/s output Windowing (ROI) to boost frame rate (both in X and Y e.g. 768k fps) Two trends: Analog naked image sensor: no sequencing or digital logic on-chip => requires complex camera system System-on-a-chip approach (as much integration as possible): on-chip ADC, sequencer, interface 6 High speed CMOS image sensors Vision 2006

7 Technology: architecture Typical analog high speed image sensor: 6T-pixel core (e.g * 1024 divided in multiple sections pixel drivers and column buffers parallel analog output tabs (128+) no timing sequencer on-chip (full external control on pixel array and read out timing). e.g. custom high-speed CIS architecture 7 High speed CMOS image sensors Vision 2006

8 Technology: architecture Typical system-on-a-chip high speed image sensor: Timing sequencer onboard Multiple ADCs on-chip Single clock input Multiple parallel digital LVDS outputs Different read-out schemes possible to fit different needs e.g. LUPA architecture 8 High speed CMOS image sensors Vision 2006

9 Classic 3T-pixel with rolling shutter Technology: 3T pixel VDD reset T1 row select PD Ipd GND Vpd Cpd T2 T3 column output Vout Volts reset PD node time Sample & Read Out 9 High speed CMOS image sensors Vision 2006

10 Technology: Pixel type: 6T High speed applications requires: snapshot shutter, high sensitivity, low PLS => solution: 6T-pixel architecture Vpix Vmem Vpix Reset T1 Sample Vpd Vpd T2 B T3 Precharge T4 A T5 Row-select T6 Vpd - Vt 10 High speed CMOS image sensors Vision 2006

11 Rolling vs. snapshot Rolling shutter Snapshot shutter Distorted motion Freezed motion Electronic snapshot shutter required for high-speed motion analysis 11 High speed CMOS image sensors Vision 2006

12 Snapshot shutter x Reset frame In parallel Line number y Integrate and Sample frame In parallel Burst readout sequential COMMON RESET Flash could occur here COMMON SAMPLE&HOLD Time axis Integration time Burst Readout time 12 High speed CMOS image sensors Vision 2006

13 Snapshot shutter True Snapshot Shutter: Pipelined and Triggered type Triggered mode (IBIS5 alike pixel): Integration frame I Readout frame I Integration frame I+1 Readout frame I+1 Pipelined mode (6T-pixel): Integration frame I+1 Integration frame I+2 Readout frame I Readout frame I+1 13 High speed CMOS image sensors Vision 2006

14 Frame rate calculation (fps) The frame rate depends on: 1. Pixel throughput in MPixels/s 2. Frame Overhead Time (FOT) typical 10us 3. Row Overhead Time (ROT) typical 300ns 4. Window size in X and Y Frame period calculation: Frame period = FOT + Nr. Lines * (ROT + Nr. Pixels * clock period) Example: LUPA-300 (VGA resolution at 80MPixels/s) Frame period = 7.8 µs + (480 * (400 ns ns * 640) = ms => fps. Frame rate increases with reduced window size in X and Y 14 High speed CMOS image sensors Vision 2006

15 Packaged high speed CIS Analog high speed CIS Digital high speed CIS 15 High speed CMOS image sensors Vision 2006

16 Examples of high speed applications: Motion analysis: Military ballistics and impact Crash tests analysis Sport analysis Machine vision inspection Slow motion digital movie capture Holographic mass data storage Applications 16 High speed CMOS image sensors Vision 2006

17 High speed motion analysis: Example of applications Crash test analysis: 17 High speed CMOS image sensors Vision 2006

18 FEATURES Ultrahigh storage densities: Application focus: Holographic data storage Optical interference technique with coherent laser beams Data storage in 3 dimensions! Storage density > 31.5 Gbits/in2 => 200 GB on DVD disk) Parallel access to data using data matrix and matrix reader instead of conventional photo diode Fast data transfers upto 1 Gbps (high speed data read out with CMOS image sensor) Durable, reliable, low cost media (polymer media) Possible due to technology breakthrough on: SLM, CMOS image sensor technology, storage media 18 High speed CMOS image sensors Vision 2006

19 Application focus: Holographic data storage RECORDING DATA A single laser beam is split into two: the signal beam that carries the data and a reference beam The data is encoded on the signal beam with a Spatial Light Modulator (SLM) Data is stored as a hologram that is recorded onto a light-sensitive storage medium at the point where the signal and reference beam intersect Angle of incidence reference beam sets depth of writing 19 High speed CMOS image sensors Vision 2006

20 Application focus: Holographic data storage Writing data 20 High speed CMOS image sensors Vision 2006

21 Application focus: Holographic data storage READING DATA A laser with the properties as the reference beam is trained on the media By changing the angle of incidence a new page is read out The laser projects the entire hologram, or page, onto a detector, a high speed CMOS image sensor Spinning disk is scanned similar to CD principle 21 High speed CMOS image sensors Vision 2006

22 Application focus: Holographic data storage High speed CMOS image sensor Reading data Read out system 22 High speed CMOS image sensors Vision 2006

23 Application focus: Holographic data storage Custom high-speed sensor for holographic read out Resolution: 1696 X * 1710 Y Pixel size: 8 um * 8 um Shutter type: Snapshot (6T-pixel) Pixel rate: 13.2 GHz (using 32 LVDS outputs) Frame rate: 485 fps 10-bit on-chip ADC Sensitivity: 650 V.m2 / W.s Power dissipation: 1100 mwatt 23 High speed CMOS image sensors Vision 2006

24 Key features on linear high-speed CISs: Application focus (2): high-speed linear sensor High speed pixel read out (> 200 MHz, with multiple outputs) Very high spatial resolution Large area imaging area (possible with stitching) Linear pixel array with high sensitivity Low power consumption High on-chip integration of digital logic (lower system cost) Typical applications: bar-code readers, dimensions measuring, position inspection devices 24 High speed CMOS image sensors Vision 2006

25 Application focus (2): high-speed linear sensor Custom high-speed linear sensor project: Resolution: 8200 * 1 line sensor Pixel size: 7 um * 7 um Image area length: 57,4 mm Chip size: 58.5 * 3.5 mm2 Snapshot shutter Line rate: 28.5k / s Data rate: 240 MHz 10-bit ADC on-chip Sensitivity: 21 V.cm2/uJ CMOS IS 25 High speed CMOS image sensors Vision 2006

26 Standard high speed sensors Name Resolution Shutter type Pixel type Pixel pitch Optical format Frame rate IBIS MP Rolling 3T 7 um 2/3 7 fps 24 fps IBIS4-A MP Rolling 3T 3.5 um 1 5 fps IBIS MP Rolling 3T 8 um F-mount 3 fps IBIS5-B MP Rolling Snapshot 4T 6.7 um 2/3 27 fps LUPA-300 VGA Snapshot 6T 9.9 um 1/2 247 fps LUPA MP Snapshot 6T 14 um fps LUPA MP Snapshot 6T 12 um F-mount 15 fps STAR k Rolling 3T 25 um 1 29 fps STAR MP Rolling 3T 15 um 1 11 fps 26 High speed CMOS image sensors Vision 2006

27 LUPA family sensors LUPA-300 Fast machine vision applications LUPA-4000 Traffic monitoring and surveillance 27 High speed CMOS image sensors Vision 2006

28 LUPA Current LUPA-1300 has 16 parallel analog output tabs + no on-chip ADCs => difficult and expensive system design Custom developed high speed technology = state-of-the-art (13.2 GPixels/s) New LUPA standard product: Use of state-of-the-art high speed IP High sensitive, high efficient snapshot shutter pixel ADCs on chip for easy integration High-speed LVDS interface 28 High speed CMOS image sensors Vision 2006

29 LUPA Samples expected Q Product brief available Specs: Resolution: 1.3 MP: 1280 X *1024 Y 14 um pixel: pipelined snapshot shutter (6Tarchitecture) 310 MHz master clock => > MP Frame rate increase with ROI read out (in X and Y) 10-bit ADC on-chip 12 LVDS output 480 Msps < 700 mwatt (ADC power 500 fps 150 pin PGA Mono and color 29 High speed CMOS image sensors Vision 2006

30 LUPA Resolution Pixel size S/N ratio Frame rate ADC Ext. dynamic range LUPA * * 14 um2 60.7dB fps No ADC on-board Multi slope + NDR LUPA * * 14 um db fps 10-bit Multi slope + NDR Output 16 analog outputs bit LVDS tabs Power PLS - Shutter efficiency 900 mwatt 1/ % < 700 mwatt 1/ % 30 High speed CMOS image sensors Vision 2006

31 Conclusion Very high speed imaging still necessary with increasing speeds and resolutions High speed imaging with on-board features for easier implementation Generic high speed image sensors for wide variety of applications New challenges on combining a very high data rate image with a lot of on-board features like LVDS and image processing 31 High speed CMOS image sensors Vision 2006

32 Thank you for your attention Questions? 32 High speed CMOS image sensors Vision 2006