NMOS linear image sensors are self-scanning photodiode arrays designed specifically as detectors for multichannel spectroscopy. The scanning
circuit is made up of N-channel MOS transistors, operates at low power consumption and is easy to handle. Each photodiode has a large active
area, high UV sensitivity yet very low noise, delivering a high S/N even at low light levels. NMOS linear image sensors also offer excellent output
linearity and wide dynamic range.
The photodiodes of S3902 series have a height of 0.5 mm and are arrayed in a row at a spacing of 50 m. The photodiodes of S3903 series also
have a height of 0.5 mm but are arrayed at a spacing of 25 m. The photodiodes are available in 3 different pixel quantities for each series: 128
(S3902-128Q), 256 (S3902-256Q, S3903-256Q), 512 (S3902-512Q, S3903-512Q) and 1024 (S3903-1024Q). Quartz glass is the standard window
material.
Features
l Wide active area
Pixel pitch: 50 m (S3902 series)
25 m (S3903 series)
Pixel height: 0.5 mm
l High UV sensitivity with good stability
l Low dark current and high saturation charge allow a long
integration time and a wide dynamic range at room temperature
l Excellent output linearity and sensitivity spatial uniformity
l Lower power consumption: 1 mW Max.
l Start pulse and clock pulses are CMOS logic compatible
Applications
l Multichannel spectrophotometry
l Image readout system
I M A G E S E N S O R
NMOS linear image sensor
Current output, high UV sensitivity, excellent linearity, low power consumption
S3902/S3903 series
0.5 mm
1.0 m
1.0 m
400 m
OXIDATION SILICON
N TYPE SILICON
P TYPE SILICON
S3902 SERIES: a=50 m, b=45 m
S3903 SERIES: a=25 m, b=20 m
b
a
KMPDC0020EA
Figure 1 Equivalent circuit
Vss
START
st
CLOCK
CLOCK
1
2
ACTIVE
PHOTODIODE
SATURATION
CONTROL GATE
SATURATION
CONTROL DRAIN
DUMMY DIODE
DUMMY VIDEO
ACTIVE VIDEO
END OF SCAN
DEGITAL SHIFT RESISTER
(MOS SHIFT RESISTER)
Figure 2 Active area structure
KMPDA0107EA
s
Absolute maximum ratings
Parameter
Symbol
Value
Unit
Input pulse (1, 2, st) voltage
V
15
V
Power consumption *
1
P
1
mW
Operating temperature *
2
Topr
-40 to +65
C
Storage temperature
Tstg
-40 to +85
C
*1: V=5.0 V
*2: No condensation
NMOS linear image sensor
S3902/S3903 series
s
Shape specifications
Parameter
S3902-
128Q
S3902-
256Q
S3902-
512Q
S3903-
256Q
S3903-
512Q
S3903-
1024Q
Unit
Number of pixels
128
256
512
256
512
1024
-
Package length
31.75
40.6
31.75
40.6
mm
Number of pin
22
22
-
Window material *
3
Quartz
Quartz
-
Weight
3.0
3.5
3.0
3.5
g
*3: Fiber optic plate is available.
s
Specifications (Ta=25 C)
S3902 series
S3903 series
Parameter
Symbol
Min.
Typ.
Max.
Min.
Typ.
Max.
Unit
Pixel pitc h
-
-
50
-
-
25
-
m
Pixel height
-
-
0.5
-
-
0.5
-
mm
Spectral response range
(10 % of peak)
200 to 1000
200 to 1000
nm
Peak sensitivity wavelength
p
-
600
-
-
600
-
nm
Photodiode dark current *
4
I
D
-
0.08
0.15
-
0.04
0.08
pA
Photodiode capacitance *
4
Cph
-
4
-
-
2
-
pF
Saturation exposure *
4,
*
5
Esat
-
180
-
-
180
-
mlx s
Saturation output charge *
4
Qsat
-
10
-
-
5
-
pC
Photo response non-uniformity *
6
PRNU
-
-
3
-
-
3
%
*4: Vb=2.0 V, V=5.0 V
*5: 2856 K, tungsten lamp
*6: 50 % of saturation, excluding the start pixel and last pixel
s
Electrical characteristics (Ta=25 C)
S3902 series
S3903 series
Parameter
Symbol
Condition
Min.
Typ.
Max.
Min.
Typ.
Max.
Unit
High V1, V2 (H)
-
4.5
5
10
4.5
5
10
V
Clock pulse (1, 2)
voltage
Low V1, V2 (L)
-
0
-
0.4
0
-
0.4
V
High
Vs (H)
-
4.5
V1
10
4.5
V1
10
V
Start pulse (st) voltage
Low
Vs (L)
-
0
-
0.4
0
-
0.4
V
Video bias voltage *
7
Vb
-
1.5
V - 3.0 V - 2.5
1.5
V - 3.0 V - 2.5
V
Saturation control gate voltage
Vscg
-
-
0
-
-
0
-
V
Saturation control drain voltage
Vscd
-
-
Vb
-
-
Vb
-
V
Clock pulse (1, 2) rise / fall time *
8
tr1, tr2
tf1, tf2
-
-
20
-
-
20
-
ns
Clock pulse (1, 2) pulse width
tpw1, tpw2
-
200
-
-
200
-
-
ns
Start pulse (st) rise / fall time
trs, tfs
-
-
20
-
-
20
-
ns
Start pulse (1, 2) pulse width
tpws
-
200
-
-
200
-
-
ns
Start pulse (st) and clock pulse
(2) overlap
tov
-
200
-
-
200
-
-
ns
Clock pulse space *
8
X
1
, X
2
-
trf - 20
-
-
trf - 20
-
-
ns
Data rate *
9
f
-
0.1
-
2000
0.1
-
2000
kHz
-
70 (-128 Q)
-
-
80 (-256 Q)
-
ns
-
110 (-256 Q)
-
-
120 (-512 Q)
-
ns
Video delay time
tvd
50 % of
saturation
*
9,
*
10
-
140 (-512 Q)
-
-
160 (-1024 Q)
-
ns
-
21 (-128 Q)
-
-
27 (-256 Q)
-
pF
-
36 (-256 Q)
-
-
50 (-512 Q)
-
pF
Clock pulse (1, 2)
line capacitance
C
5 V bias
-
67 (-512 Q)
-
-
100 (-1024 Q)
-
pF
-
12 (-128 Q)
-
-
12 (-256 Q)
-
pF
-
20 (-256 Q)
-
-
24 (-512 Q)
-
pF
Saturation control gate (Vscg)
line capacitance
Cscg
5 V bias
-
35 (-512 Q)
-
-
45 (-1024 Q)
-
pF
-
7 (-128 Q)
-
-
10 (-256 Q)
-
pF
-
11 (-256 Q)
-
-
16 (-512 Q)
-
pF
Video line capacitance
C
V
2 V bias
-
20 (-512 Q)
-
-
30 (-1024 Q)
-
pF
*7: V is input pulse voltage (refer to figure 8)
*8: trf is the clock pulse rise or fall time. A clock pulse space of
rise time/fall time - 20
ns (nanoseconds) or more should be
input if the clock pulse rise or fall time is longer than 20
ns. (refer to figure 7)
*9: Vb=2.0 V, V=5.0 V
*10: Measured with C7883 driver circuit.
NMOS linear image sensor
S3902/S3903 series
Figure 3 Dimensional outlines (unit: mm)
S3902-128Q, S3903-256Q
S3902-256Q, S3903-512Q
0.51
25.4
2.54
3.0
31.75
10.4
5.2 0.2
5.2 0.2
3.2 0.3
ACTIVE AREA
6.4 0.5
0.25
10.16
1.3 0.2*
PHOTOSENSITIVE
SURFACE
* Optical distance from the outer surface
of the quartz window to the chip surface
0.51
25.4
2.54
3.0
ACTIVE AREA
12.8 0.5
6.4 0.3
31.75
10.4
5.2 0.2
5.2 0.2
0.25
10.16
1.3 0.2*
PHOTOSENSITIVE
SURFACE
* Optical distance from the outer surface
of the quartz window to the chip surface
KMPDA0108EA
KMPDA0109EA
S3902-512Q, S3903-1024Q
0.51
25.4
3.0
40.6
10.4
5.2 0.2
5.2 0.2
12.8 0.3
ACTIVE AREA
25.6 0.5
0.25
10.16
1.3 0.2 *
PHOTOSENSITIVE
SURFACE
* Optical distance from the outer surface
of the quartz window to the chip surface
2.54
KMPDA0110EA
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
END OF SCAN
1
2
3
4
5
6
7
8
9
10
11
22
21
20
19
18
17
16
15
14
13
12
2
1
st
Vss
Vscg
NC
Vscd
Vss
ACTIVE VIDEO
DUMMY VIDEO
Vsub
Vss, Vsub and NC should be grounded.
KMPDC0056EA
Figure 4 Pin connection
NMOS linear image sensor
S3902/S3903 series
0.3
0.2
0.1
0
200
400
600
800
1000
1200
WAVELENGTH (nm)
PHOTO SENSITIVITY (A/W)
(Ta=25 C)
Terminal
Input or output
Description
1, 2
Input
(CMOS logic compatible)
Pulses for operating the MOS shift register. The video data rate is
equal to the clock pulse frequency since the video output signal is
obtained synchronously with the rise of 2 pulse.
st
Input
(CMOS logic compatible)
Pulse for starting the MOS shift register operation. The time interval
between start pulses is equal to the signal accumulation time.
Vss
-
Connected to the anode of each photodiode. This should be
grounded.
Vscg
Input
Used for restricting blooming. This should be grounded.
Vscd
Input
Used for restricting blooming. This should be biased at a voltage
equal to the video bias voltage.
Active video
Output
Video output signal. Connects to photodiode cathodes when the
address is on. A positive voltage should be applied to the video
line in order to use photodiodes with a reverse voltage. When the
amplitude of 1 and 2 is 5 V, a video bias voltage of 2 V is
recommended.
Dummy video
Output
This has the same structure as the active video, but is not
connected to photodiodes, so only spike noise is output. This
should be biased at a voltage equal to the active video or left as an
open-circuit when not needed.
Vsub
-
Connected to the silicon substrate. This should be grounded.
End of scan
Output
(CMOS logic compatible)
This should be pulled up at 5 V by using a 10 k resistor. This is a
negative going pulse that appears synchronously with the 2
timing right after the last photodiode is addressed.
NC
-
Should be grounded.
10
5
10
2
10
1
10
0
10
1
10
2
10
3
10
4
10
3
10
2
10
1
10
0
OUTPUT CHARGE (pC)
EXPOSURE (lx s)
(Typ. Vb=2 V, V =5 V, light source: 2856 K)
S3903 SERIES
S3902 SERIES
SATURATION EXPOSURE
SATURATION
CHARGE
KMPDB0149EA
Figure 5 Spectral response (typical example)
Figure 6 Output charge vs. exposure
KMPDB0117EA
s Construction of image sensor
The NMOS image sensor consists of a scanning circuit made
up of MOS transistors, a photodiode array, and a switching
transistor array that addresses each photodiode, all integrated
onto a monolithic silicon chip. Figure 1 shows the circuit of a
NMOS linear image sensor.
The MOS scanning circuit operates at low power consump-
tion and generates a scanning pulse train by using a start
pulse and 2-phase clock pulses in order to turn on each ad-
dress sequentially. Each address switch is comprised of an
NMOS transistor using the photodiode as the source, the
video line as the drain and the scanning pulse input section
as the gate.
The photodiode array operates in charge integration mode
so that the output is proportional to the amount of light expo-
sure (light intensity integration time).
Each cell consists of an active photodiode and a dummy
photodiode, which are respectively connected to the active
video line and the dummy video line via a switching transis-
tor. Each of the active photodiodes is also connected to the
saturation control drain via the saturation control transistor,
so that the photodiode blooming can be suppressed by
grounding the saturation control gate. Applying a pulse sig-
nal to the saturation control gate triggers all reset. (See "Aux-
iliary functions".)
Figure 2 shows the schematic diagram of the photodiode
active area. This active area has a PN junction consisting of
an N-type diffusion layer formed on a P-type silicon substrate.
A signal charge generated by light input accumulates as a
capacitive charge in this PN junction. The N-type diffusion
layer provides high UV sensitivity but low dark current.
NMOS linear image sensor
S3902/S3903 series
s Driver circuit
S3902/S3903 series do not require any DC voltage supply
for operation. However, the Vss, Vsub and all NC terminals
must be grounded. A start pulse
st and 2-phase clock pulses
1, 2 are needed to drive the shift register. These start and
clock pulses are positive going pulses and CMOS logic com-
patible.
The 2-phase clock pulses
1, 2 can be either completely
separated or complementary. However, both pulses must not
be "High" at the same time.
A clock pulse space (X
1
and X
2
in Figure 7) of a "rise time/fall
time - 20" ns or more should be input if the rise and fall times
of
1, 2 are longer than 20 ns. The 1 and 2 clock pulses
must be held at "High" at least 200 ns. Since the photodiode
signal is obtained at the rise of each
2 pulse, the clock pulse
frequency will equal the video data rate.
The amplitude of start pulse
st is the same as the 1 and 2
pulses. The shift register starts the scanning at the "High"
level of
st, so the start pulse interval determines the length of
signal accumulation time. The
st pulse must be held "High"
at least 200 ns and overlap with
2 at least for 200 ns. To
operate the shift register correctly,
2 must change from the
"High" level to the "Low" level only once during "High" level of
st. The timing chart for each pulse is shown in Figure 7.
s End of scan
The end of scan (EOS) signal appears in synchronization
with the
2 timing right after the last photodiode is addressed,
and the EOS terminal should be pulled up at 5 V using a 10
k
resistor.
tvd
tpw 1
tpw 2
tpw s
st
V s (H)
V s (L)
V 1 (H)
V 1 (L)
V 2 (H)
V 2 (L)
1
2
END OF SCAN
st
1
2
tr s
tf s
tr 1
tf 1
X1
X2
t ov
tf 2
tr 2
ACTIVE VIDEO OUTPUT
KMPDC0022EA
Figure 7 Timing chart for driver circuit
s Signal readout circuit
There are two methods for reading out the signal from an NMOS
linear image sensor. One is a current detection method using
the load resistance and the other is a current integration method
using a charge amplifier. In either readout method, a positive
bias must be applied to the video line because photodiode
anodes of NMOS linear image sensors are set at 0 V (Vss).
Figure 8 shows a typical video bias voltage margin. As the clock
pulse amplitude is higher, the video bias voltage can be set
larger so the saturation charge can be increased. The rise and
fall times of the video output waveform can be shortened if the
video bias voltage is reduced while the clock pulse amplitude is
still higher. When the amplitude of
1, 2 and st is 5 V, setting
the video bias voltage at 2 V is recommended.
To obtain good linearity, using the current integration method is
advised. In this method, the integration capacitance is reset to
the reference voltage level immediately before each photodiode
is addressed and the signal charge is then stored as an integra-
tion capacitive charge when the address switch turns on. Fig-
ures 9 and 10 show a typical current integration circuit and its
pulse timing chart. To ensure stable output, the rise of a reset
pulse must be delayed at least 50 ns from the fall of
2.
Hamamatsu provides the following driver circuits and related
products (sold separately).
KMPDB0043EA
Figure 8 Video bias voltage margin
4
0
6
8
10
4
5
6
7
8
10
CLOCK PULSE AMPLITUDE (V)
VIDEO BIAS VOLTAGE (V)
2
9
MIN.
VIDEO BIAS RANGE
MAX.
RECOMMENDED BIAS
Product
name
Type No.
Content
Feature
C7883
High-speed
driver circuit
C7883G
C7883
+ C8225-01
High-speed operation
Single power supply
(+15 V) operation
Compact
C7884
Precision
driver circuit
C7884G
C7884
+ C8225-01
Low noise
Good output linearity
Boxcar waveform output
C7884-01
High precision
driver circuit
Driver
circuit
C7884G-01
C7884-01
+ C8225-01
Ultra-low noise
Good output linearity
Boxcar waveform output
Pulse
generator C8225-01
C7883,
C7884 series
Cable
A8226
C7883 to
C7885 series BNC, length 1 m
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