the european low flux image sensor (elfis)€¦ · the european low flux image sensor (elfis) bart...
Post on 30-Apr-2020
10 Views
Preview:
TRANSCRIPT
The European Low Flux Image Sensor
(ELFIS)
Bart Dierickx, Ajit Kalgi, Alexander Klekachev, Jan Vermeiren
Outline
1. Short company introduction
2. ELFIS Key features
3. High Dynamic Range (HDR) images
4. HDR movie
5. HDR + Global Shutter operation
6. Conclusions
5 September 2019 2
Image sensor landscape
5 September 2019 Caeleste Property 3
R&D center imaging
Image sensor design & manufacture
Image application
Caeleste’s Mission
Caeleste Property
Be the supplier
of
beyond state-of-the-art
custom-designed
CMOS image sensors
Address
Hendrik Consciencestraat 1b, 2800 Mechelen, Belgium
Representation
Europe
D + A + CH: EURECA Messtechnik GmbH
UK + Ireland: Alrad
F + E + I: ATD
Russia: NPK Photonica, St. Petersburg
Israël: Kedem Technologies
America
USA: RA Paramount LLC
Asia
China: Luster Lighttech
India: ATOS – Instruments marketing Services
Japan: Kiyoshi Tabata
Korea: SOLTRON, Seoul
Who we are
Caeleste Property
Business focus
Caeleste Property
Scientific &
Space
Medical &
Life Science
Caeleste’s
custom-designed
differentiation
Military
Industrial &
Professional
Imaging
Growing the Business
From Consultant to full turn-key Supplier
Caeleste Property
2016 Fastest
Growing Hardware
Company in our
region
Deloitte’s
Fast-50 -
2016
Company owned by founders/personnel, no external capital
No exit scenarios; long term view and continuity
Allows strong focus on company’s DNA: custom, high-end imaging
ELFIS - Key features
2.
5 September 2019 8
A sensor (system)
5 September 2019 9
Satellite as a sensor
Instrument as a sensor
Integrated sensor
Introduction
• The image sensor – together with the optics -
are the key elements of a remote sensing instrument.
• What you loose in noise or resolution, you never gain back
5 September 2019 10
Original Low resolution High Noise
Justification
The ELFIS imager is the first image sensor ever combining following features
1. True HDR or “MAF HDR” (Motion Artifact Free High Dynamic Range)
2. IWR Global shutter using GS CMOS technology, which
Allows low noise readout by the use of on-chip CDS (correlated double
sampling)
Enabling Global Shutter without dark current penalty
3. BSI (Backside illumination) realizing near 100% QE (quantum efficiency) x
FF (fill factor)
4. TID (total ionizing dose) radiation hard design
It is developed under ESA contract 4000116089 “European Low Flux Image Sensor”, in collaboration with
LFoundry (It) and Airbus (Fr)
5 September 2019 11
ELFIS Architecture
5 September 2019 12
ELFIS pixel
5 September 2019 13
Pixel topology, as in US patent 9819882
ELFIS photo response of HG and LG signals
14
Raw data of both signal rangesAfter applying a gain factor on
the LG data
80%
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
200 300 400 500 600 700 800 900 1000 1100
Qu
antu
m E
ffic
ien
cy
wavelenght [nm]
Quantum Efficiency FSI versus BSI
LF BSI thick epi UV
LF BSI thick epi VIS
XC018 standard VIS
XC018 standard UV
BSI versus FSI: QE
5 September 2019 15
>90% peak QE
Significantly
enhanced UV
and blue
sensitivity
No fringes in UV
and visible
“etaloning”
(interference in
Si-layer)Interference in
SiN and SiO2
layers
80%+
peak QE if
no metals
Good NIR
respons
depends on Si
thickness12µm
6µm
Key specifications measured
Geometry
15µm pixel pitch
1920x1024 pixels
16 parallel differential output channels
BSI
Stitching compatible design
Electrical performance
40MHz pixel rate per output channel
500mW at max speed
5 September 2019 16
Electro-optical
QFW 6000e- and 160 000e- in IWR;
6000e- and 320 000e- in ITR
Qnoise 6.5eRMS in nominal operation
Peak QE > 90%
MTF >60% for thin layer BSI
PLS >200:1 for thin layer BSI, >500:1 for
thick epi
Idark @RT:
PPD:60e/s
SN:80e/s
FD=140e/s
HDR images
3.
5 September 2019 17
Setup
5 September 2019 18
All images are taken in IWR (global
shutter “integrate while read”),
with tframe = tint = 30ms.
19
High gain (HG)
sub-frame
Low gain (LG)
sub-frame
Processing the LG and HG (sub-)frames into a HDR frame
20
Displaying the HDR frame
The “raw” HDR frame histogram
The “equalized” histogram
HDR movie
4.
5 September 2019 21
See also https://www.youtube.com/watch?v=_SUg1v9ZSjI
22
Conditions:
IWR tframe=tint = 30ms thus fframe=33Hz
Looking through the window to sunlit buildings
Nikon 28mm lens, diaphragm set to 22
On-chip CDS and dark frame subtraction
No PRNU correction, no linearization was
done. Two defect rows were corrected
The HDR image is created by a weighted
interpolation between the HG and the LG
frames
The image is “histogram equalized” for display
HDR+GS pixel operation
5.
5 September 2019 23
HDR by combining two “normal” DR ranges
24
High QFW range:
DR=320000/50≈6400:1
Low QFW range:
DR=6000/5 ≈ 1200:1
Combination
DR=320000/5 ≈ 64000:1 or 96dB
1
10
100
1000
1 10 100 1000 10000 100000 1000000
no
ise
[e- R
MS]
photo charge [e-]
3.125µV/e-
165µV/e-
HDR
Operation of the ELFIS HDR+GS pixel, simplified
25
For the sake of clarity we explain the ELFIS pixel operation
using a simplified version of its topology as shown at the
right.
On the next slide we show a vertical cross section of this
pixel along the red dashed line.
On the slides thereafter we show the potential diagram in
the Silicon along the dashed red line, from FD to FD.
Abbreviations
PPD: pinned photodiode
SN: storage node
TG: transfer gate(s)
FD: floating diffusion
CN: capacitor node
M: merge transistor
VDDpix: pixel supply voltage
PPD
TG1
TG2
SN
FD
TG3
M
CN
VDDpixColumn output
Reset
select
During integration photocharge is accumulated in the photodiode.
The TG3 gate voltage is set to the intermediate “overflow barrier” operation point.
When the photodiode is too full, charge overflows to the capacitor node
blue: charge fitting in the PPD
red: charge overflowing into the capacitor node.
Ф
Photo-charges
FD
PPD
TG3
CN
M
FD VDDpix
SN
TG1
TG2
R
PPD
TG1
TG2
SN
FD
TG3
M
CN
VDDpixColumn output
Reset
select
End of integration time:
1) stop overflow over TG3
2) transfer PPD (blue) charge to the SN using TG1
FD
PPD
TG3
CN
M
FD VDDpix
SN
TG1
TG2
PPD
TG1
TG2
SN
FD
TG3
M
CN
VDDpixColumn output
Reset
select
Ф
End of integration time:
1) stop overflow over TG3
2) transfer PPD (blue) charge to the SN using TG1
FD
PPD
TG3
CN
M
FD VDDpix
SN
TG1
TG2
PPD
TG1
TG2
SN
FD
TG3
M
CN
VDDpixColumn output
Reset
select
Ф
As the photocharge of the previous integration time is now in available in the SN
and the CN, if can be read out. The readout of the imager happens row-by-row
or in “rolling readout”. The select transistors of the rows to be read out are
activated, the reset transistors are turned off, and then three voltage levels are
put on the column bus: “R1”, “S1” and “S2”.
“R1” is reset level as present on the FD immediatedly after releasign the reset.
FD
PPD
TG3
CN
M
FD VDDpix
SN
TG1
TG2
output
Select
“R1”
PPD
TG1
TG2
SN
FD
TG3
M
CN
VDDpixColumn output
Reset
select
Ф
Then the gate TG2 toggled off-on-off, allowing the charge in the SN to
transfer to the FD.
This is the “S1” signal level, representing the “blue” charge.
FD
PPD
TG3
CN
M
R
FD VDDpix
SN
TG1
TG2
PPD
TG1
TG2
SN
FD
TG3
M
CN
VDDpixColumn output
Reset
select
Ф
This is the “S1” signal level, representing the “blue” charge.
In the ELFIS imager, “R1” and “S1” are output as a combined differential
signal (S1-R1) & (R1-S1). In this way we perform “CDS” (correlated double
sampling), a technique that cancels the FD’s kTC noise and reduces the
FPN (fixed pattern noise).
FD
PPD
TG3
CN
M
R
FD VDDpix
SN
TG1
TG2
“S1”
output
Select
PPD
TG1
TG2
SN
FD
TG3
M
CN
VDDpixColumn output
Reset
select
Ф
Then the Merge transistor is closed, shunting the FD and the CN. All
photocharge, previously divided over the SN (blue) and the CN (red) is
now reunited.
This signal is “S2”, being the LG or high QFW signal level. We do not apply
CDS on S2; still S2 is readout differentially as (S2-ref)&(ref-S2).
FD
PPD
TG3
CN
M
FD VDDpix
SN
TG1
TG2
“S2”
output
Select
PPD
TG1
TG2
SN
FD
TG3
M
CN
VDDpixColumn output
Reset
select
Ф
Conclusions
6.
5 September 2019 33
Conclusions
• The operation of the ELFIS sensor is fully demonstrated
• HDR operation
• Global shutter operation
• Further optimizations:
• Saturation of the storage node
• Processing on thick epi layer
• Planned activities:
• Radiation testing: TID and SEE
ESA contract 4000116089 “European Low Flux Image Sensor”, with LFoundry (It) and Airbus (Fr)
5 September 2019 34
Questions ?
5 September 2019 35
top related