Does STAR-250 suffer from incomplete reset (image lag)? does come that

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Does STAR-250 suffer from incomplete reset (image lag)? does come that

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Frequently Asked Questions about STAR-250 Device AN5012
Does STAR-250 suffer from incomplete reset (image lag)? does come that first image after initialization banding effect?. possible reduce power consumption STAR-250? there gradient from left right dark image? first every image darker than others? internal bias resistor values depend temperature? Where pixel located package? frame rate STAR-250 calculated?
Does STAR-250 suffer from incomplete reset (image lag)? With default settings data sheets STAR-250 suffers from image mainly visible higher gains. Image defined incomplete reset previous frame therefore saturated parts previous frame complete reset dark level beginning current frame. This image image associated with "soft reset" operation. I.e., pixel, both supply (=VPIX) VRESET (=VDD) equal (5V). During reset, reset MOSFET weak inversion, will only asymptotically reach equilibrium- absence current. Response small excursions this equilibrium happens with large time constants.
Reset
Read
Figure Pixel schematic with Reset MOSFET
This solved bias current operating pixels "hard reset". This accomplished avoiding that reset MOSFET goes weak inversion; this done e.g., turning VPIX down about 3.3.5 VRESET-VPIX Vth, reset MOSFET linear regime during reset, weak inversion, causing thus image behaves current source with long time constant. VRESET-VPIX Vth, reset MOSFET linear regime during reset, acts (+/-) ideal switch. value VPIX highest (starting) voltage photodiode. light dark current voltage photodiode will gradually drop. pixel's (highest) output voltage (VRESET Vth) (VPIX Vth) whichever lower. This explains fact that voltage range change little hard reset mode course, voltage that sensors output goes through some additional stages.).
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does come that first image after initialization banding effect? Figure below shows scene wall where banding present. This banding only seen very first image acquired after initialization. lines
lines
Figure STAR-250 Image with Banding reason darker offset lines influence number resets (one row) level where pixels reset too. exposure sensor between synchronization reset pointer synchronization read pointer explained data sheets. Suppose that exposure n-lines than will first n-lines first image have darker offset compared other lines. During initial reset these lines other lines read yet. Because that RESET pulse only pulsed once that causes different load internal reset supply compared residual lines image. There's only reset pulse timing during reset first lines (only pulses applied; Figure Starting from line reset pulses applied each (both black pulses; Figure This affecting reset level which line reset (due different load reset supply) hence seen image illumination difference. This effect only visible first frame that read after initialization. second frame reset timing same each banding effect seen. advised ignore first frame that read after initialization since work-around found avoid banding effect.
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Lgn: firs -lin itia rtin
Figure Timing STAR-250 Sensor possible reduce power consumption STAR-250? Despite fact that there standby STAR-250 sensor there still possibilities reduce power consumption. general there ways reduce power consumption. Firstly implement kind standby mode since applications acquiring images time. Secondly reduce pixel rate MHz) continuously acquire images thirdly combine first solutions (lower pixel rate combination with standby mode). first reduce overall power consumption implement kind stand mode without power-down complete sensor. Since output amplifier internal have highest part total power consumption (together they consume 70-80% total power consumption) both parts have separate supply reduce power consumption stand mode normal power consumption switching (0V) these supplies during standby. other supplies should still supplied with their nominal power level (5V) timing signals should pulsed continuously during `standby' period. Supply Name VDD_ANA VDD_DIG VDD_AMP VDD_RES VDD_PIX VDD_ADC_DIG VDD_ADC_ANA Power consumption Normal Level 100% `Standby' Level
Note that this power reduction method needs controllable power supply level VDD_AMP (pin VDD_ADC_ANA (pin 56). level these power supplies switched between (nominal) (stand by). After `standby' when level VDD_AMP VDD_ADC_ANA switched back from takes least before STAR250 sensor back normal operation conditions. second reduce power consumption reduce pixel rate STAR-250 sensor. This lower pixel rate allows have higher bias resistor values some bias nodes which reduces bias current thus also power consumption. table below compares nominal setting bias resistors pixel rate) bias setting optimized MHz.
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Bias Resistor NBIASARR PBIAS NBIAS_AMP NBIASANA NBAISANA2 PBIASDIG2 PBIASENCL PBIASDIG1
Nominal Value MHz) 500k 100k 100k 100k 100k
Optimized Value MHz) 500k 100k 200k 250k 100k 100k 250k
bias settings other pixel rate frequencies recalculated accordingly. reduce power consumption further combine methods explained above (reduced pixel rate `standby' period). there gradient from left right dark image? When looking highly amplified dark frame taken with STAR-250 dark gradient from left right (left image darker right image).
Figure Dark Frame Gradient Cypress still investigating possible cause possible countermeasures taken avoid this gradient. moment solution provided yet. first every image darker than others? first every image small offset compared other rows STAR-250. average response first maximum darker compared normal response other rows. moment solution provided yet. internal bias resistor values depend temperature? Yes, internal bias resistors value depends temperature sensor temperature dependency poly sheet resistance. This most important input range since this range with resistor ladder external resistors (VLOW_ADC VHIGH_ADC) internal ADC. internal resistor value increases approximately with increasing temperature.
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Temp. [°C]
RADC 1150 1400
_VLOW
Figure Ladder Resistor Setting Where pixel located package? STAR-250 sensor bonded 84-pin JLCC package (see data sheets paragraph detailed package drawing). centre pixel array placed centre ceramic package. Pixel located right corner Figure
Figure Figure Placement STAR-250 Sensor
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frame rate STAR-250 calculated? windowing functionality STAR-250 frame rate depending resolution (region Interest) that read out. Frame period (Nr. Lines (RBT pixel period Pixels)) with: Lines: Number Lines read each frame (Y). Pixels: Number pixels read each line (X). RBT: Blanking Time (typical). Pixel period: (typical). Example: read time full resolution nominal speed pixel rate): Frame period (512 (3.2 512)) 34.4 fps.
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Does STAR-250 suffer from incomplete reset (image lag)? does come that

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