Judson Preamp
PA-5, PA-9
PA-6, PA-9
PA-7, PA-9
Detector Shunt
Impedance (ohms) Recommended
Op Amp
LT 1028,
Discrete FET
OP27,
Discrete FET
OPA111, LF356,
Discrete FET
1 to 500
500 to 2000
2000
Reverse Bias Voltage VR (Volts)
0 2 4 6 8 10
Relative Capacitance (%)
20
40
60
80
100
RL
(50ohm -
1Kohm)
Vbias
+5V
to
+10V
Rbias
(~10Kohm)
Capacitor
.01 to .1 µF
(ceramic) Coax
Cable to
Oscillo-
scope
J12 Series
photodiode
10
11
10
9
10
10
1234
Wavelength (µm)
10
12
10
8
J12TE3 (-65°C)
J12TE2 (-40°C)
J12 (22°C)
J12TE1 (-20°C)
J12TE4 (-85°C)
IS
RF > 10x RD
Vo = IS • RF
Vos
+
-
Ios
Detector
Judson Technologies
PB 220
October 2000
J12 SERIES
INAS DETECTORS
Operating Instructions
Operating Circuit
The recommended operating
circuit for most applications is an
operational amplifier in a negative-
feedback transimpedance
configuration. The feedback circuit
converts the detector output current
to a voltage, while the op-amp
maintains the detector near zero-volt
bias for lowest noise. (Figure 1.0).
Because RD varies significantly
with temperature, selection of the
proper op-amp will depend on the
detector operating temperature as
well as the desired bandwidth. The
feedback resistor RF should be at
least 10x greater than RD for best
signal-to-noise ratio. Judson has
preamplifiers for optimum
performance with each detector type.
For high frequency applications,
the detector may be reverse biased
and terminated into a low impedance
load. Maximum reverse bias is 1 volt.
(See Figure 3.0).
Detectivity vs Wavelength
for J12 Series High Speed Operating Circuit
Recommended Preamplifiers
The PA5, PA6 and PA7 have
adjustable gain and low noise.
Preamplifiers should be picked by the
detector shunt impedance at the
optimal operating temperature for a
particular application (Table 1). The
PA9 should be used where high
frequency response and low noise are
required. The PA9 may not be
suitable for DC applications due to its
high input offset voltage.
Figure 2.0
Frequency Response
The feedback resistance RF,
combined with the detector
capacitance and dynamic impedance,
determines the frequency response of
the system. Capacitance and
impedance values are provided on
the data sheet supplied with each
detector.
Figure 3.0
Preamp Selection vs Shunt Selection Impedance
Table I
≥
Typical J12 Series Operating Circuit
Figure 1.0
D* (λ, 1KHz, 1Hz) (cm√Hz/W)
I
V
I x R = V
light F out
I light
o
I dark
o
Photon
.01 V
-.01 V
R = dV
dI
D
dV
dI
1.50
1.25
1.00
0.75
0.50
0.25
0.00
Responsivity (A/W)
Wavelength (µm)
22°C
-20°C
-40°C
-65°C
-85°C
4.0
3.53.0
2.5
2.0
Detector/
Aperture Chopper Heat Sink Preamp
R
F
HSA2 Assembly
500°K
Blackbody
W ave Digital T C5
Scope Analyzer Multimeter Temp.
Controller
J12 SERIES
INAS DETECTORS
Operating Instructions
Figure 7.0
J12TE Detector Response vs Wavelength & Temperature
Blackbody Responsivity (RBB)
Defined as the current produced by a detector in response
to the radiant power on the detector (amps/watt) (Figure
6.0). For the test setup, RBB is equal to Vout/(HBBADGain)
where HBB is the blackbody irradiance in watts/cm2, AD is
the area of the detector in cm2, Vout is the rms signal voltage
at the output of the preamplifier in volts, and Gain is the
gain of the preamplifier in volts/amp.
Detector Response to Incoming Photons
Figure 6.0
Detector Shunt Impedance
Effective dynamic impedance of the detector at operating
temperature, measured at 0 volts bias (Figure 5.0).
Figure 5.0
Test Conditions
All Judson detectors undergo stringent quality control
testing before shipment. A test setup (Figure 4.0) is
used to check J12 Series detectors for responsivity (R)
and detectivity (D*).
A copy of the test data is provided with each detector
and includes the following test condition information:
Flux Density (H)
Actual rms total power in watts/cm2 irradiating the
detector surface. Equal to FσT4BB/As/πd2 where F is the
rms constant of the chopper (≈ 0.36), is the Stefan-
Boltzman constant, TBB is the blackbody temperature, As
is the aperture area and d is the source-to-detector
distance.
Chopping Frequency
Frequency of chopper for modulating the blackbody
source signal.
Blackbody Temperature
Absolute temperature in °K of the blackbody source
used for response test.
Background Temperature
Room temperature in °K.
Detector Temperature
Operating temperature of the detector during the test.
Figure 4.0
Peak Responsivity (Rλλ
λλ
λ)
Responsivity in amps/watt at the wavelength of peak
response. Related to blackbody responsivity by Rλ= RBBG,
where the constant G is the ratio of total blackbody power
to the power “utilized” by the detector. For InSb detectors
without filters, G ≈ 5.5 and is determined as follows:
G-1 = 1 N(λ,TBB) R(λ) dλ
WBB R(λp)
where N(λ,TBB) is the irradiance at λ in w/cm2/µ and WBB is
the total blackbody irradiance in w/cm2.
100%
0
50%
-1 -.5 0 +1
Active Area Position (mm)
Relative Response
+.5
Active A rea
-40°C
22°C
Contact
Contact
0°C
Direction
of Spot
Scan
Across
Surface
Detector
Ring
Contact
Active A rea Position
"Light Spot"
From
Source
0 +1 mm+.5-1 -.5
Calculating Detector Response Uniformity
Output signal current from detector Is is defined as:
Isignal = Iphoton Detector shunt (Ω) - Detector series (Ω)
Detector shunt (Ω)
For J12-5AP-R02M
Isignal = 1.25A/W = .5A/W
For J12TE2-8B6-R02M
Isignal = 1.25A/W = 1.21A/W
Series resistance is approx. 0Ω at contact. Total series
resistance is approx. 5Ω - 10Ω, approx. 6Ω nominal.
Therefore, response uniformity is a fucntion of the
voltage divider in the equivalent circuit RD and RS.
J12 SERIES
INAS DETECTORS
Operating Instructions
Detector Equivalent Circuit For a J12-5AP-R02M:
= = = 40% response at center
For a J12-5SP-R02M:
= = = 94% response at center
• High ratio of Detector Shunt Impedance to series
resistance = high uniformity.
J12 Series Detector Noise
• Noise due to shunt impedance or noise current Johnson
(thermal) noise
int =
where Rsh = detector shunt resistance or feedback
resistance whichever is lower.
K = Boltzmans Constant (1.38 x 10-23 joules/°K)
T = Operating Temperature (°K)
∆f = Noise Equivalent Bandwidth (Hertz)
Rsh = Shunt Resistance (ohms)
• Noise due to Capacitance at a frequency
For a photovoltaic detector junction capacitance can
dominate noise at high frequency.
in = (Preamp voltage noise floor) (2πfCD)
RD - RS
RD
RD - RS
RD
10-6
10 4
10
100-6
100
√4KT∆f
Rsh
200-6
200
( )
10-6
10
( )
( )
94
100
L
O
A
D
I
S
Iph
V
D
C
D
R
D
R
S
I
ph
= Current generated by incident photons
V
D
= Actual voltage across diode junction
C
D
= Detector junction capacitance
R
D
= Detector shunt resistance
R
s
= Detector series resistance
I
s
= Output signal current
Rbias
Vbias
-0.1V
40
20
0
-20
-40
-60
-20 020 40 60 80
Detector Temperature TD (°C)
100
Heat Sink Temperature T (°C)
H
Cooler Current = 1 Amp
Cooler Current = 0.5 Amp
1" dia
0.25
Heat Sink
for 8B6, 66S pkgs
1M
100K
10K
1K
100-80 -60 -40 -20 0 +20 +40
Detector Temper ature (°C)
30
10
-10
-30
-50
-70
0 0.2 0.4 0.6 0.8
1
2
1.0
Cold Side Temperature TD (°C)
1.2
0.25mm
2.0mm
0.25mm
2.0mm
0.25mm
2.0mm
Cooler Current I (Amps)
Hot side = 27°C
TD vs I
Cooler Voltage V (Volts)
3
Cooler V vs I
1-Stage
2-Stage
3-Stage
1M
100K
10K
1K
100
10
0-80 -60 -40 -20 0 +20 +40
Detector Temperature (°C)
R + R
D
S
250µm dia.
1mm dia.
2mm dia.
J12 SERIES
INAS DETECTORS
Operating Instructions
Temperature Effects
Cooling an InAs photodiode reduces noise and
improves detectivity.
Cooling also increases shunt resistance RD allowing
more of the photocurrent Iph to reach the contact ring.
The result is an increase in the diode response.
For high-power applications such as pulsed laser
detection, cooling is generally not necessary. For
sensitive, low-power applications such as temperature
measurements, the InAs detector should be cooled or at
least temperature-stabilized.
Stabilizing the temperature near 22°C room
temperature will not improve performance, but will
prevent changes in detector response due to ambient
temperature drift.
Thermoelectric Cooler Operation
Figure 8.0 shows typical power requirements for the TE1,
TE2 and TE3 coolers. The built-in thermistor can be
used to monitor or control the temperature. Figure 10.0
shows typical thermistor resistance vs. temperature
values. Sensitivity, cutoff wavelength and response
uniformity are all functions of temperature. Detector
temperature should be optimized for a particular
application.
Shunt Resistance vs Temperature
Detector Thermistor Value (KΩ)
Temperature Min. Typ. Max.
22°C 1.3
-40°C 15.0 30.0 40.0
-65°C 60.0 85.0 100.0
Figure 10.0
Figure 8.0
Figure 9.0
Shunt Resistance RD (Ω)
Thermistor Resistance (KΩ)
Active
Size
(dia.)
Cutoff
Wave-
length
@ λco
Respon-
sivity
@ λp
Shunt
Resistance
R
D
@ V
R
= 10mV
Maximum
NEP
@ λ
peak
and 1KHz
Minimum
D*
@ λ
peak
and 1KHz
Capacitance
C
D
@ V
R
= 0V
(50%) Min. Typ. (Jones)
(mm) (µm) (A/W) (ohms) (ohms)
(pW/Hz
1/2
)(cmHz
1/2
W
-1
)
(pF)
J12 Series Room Temperature InAs
J12-18C-R250U 420002 0.25 1.5 200 300 6.0 3.7E9 50
J12-18C-R01M 420003 1.00 22°C 3.60 1.0 15 25 33 2.7E9 400 LD2
J12-5AP-R02M 420011 2.00 0.8 5 10 71 2.5E9 1600
J12TE1 Series One-Stage Thermoelectrically Cooled InAs
J12TE1-37S-R250U 420088 0.25 1.5 2000 3000 1.8 1.3E10 50
J12TE1-37S-R01M 420061 1.00 -20°C 3.50 1.5 200 300 5.6 1.6E10 400
J12TE1-37S-R02M 420065 2.00 1.25 50 90 13 1.3E10 1600
J12TE2 Series Two-Stage Thermoelectrically Cooled InAs
J12TE2-66D-R250U 420083 0.25 12K 24K .69 3.2E10 50
J12TE2-66D-R01M 420041 1.00 -40°C 3.45 1.5 1.2K 2.4K 2.2 4.1E10 400
J12TE2-66D-R02M 420089 2.00 300 500 4.4 4.1E10 1600
J12TE3 Series Three-Stage Thermoelectrically Cooled InAs
J12TE3-66D-R250U 420081 0.25 160K 320K .18 1.2E11 50
J12TE3-66D-R01M 420056 1.00 10K 20K .71 1.2E11 400
J12TE3-66D-R1.5M 420063 1.50 5K 10K 1.0 1.3E11 800
J12TE3-66D-R02M 420098 2.00 2.5K 5K 1.4 1.2E11 1600
J12TE4 Series Four-Stage Thermoelectrically Cooled InAs
J12TE4-3CN-R250U 0.25 400K 800K .11 2.1E11 50
J12TE4-3CN-R01M 420093 1.00 -85°C 3.30 1.5 25K 50K .43 2.1E11 400
J12TE4-3CN-R02M-B 2.00 6.5K 13K .84 2.1E11 1600
Optional
Packages
and
Accessories
HS1,
CM21
HS Amp, HS1,
CM21,
CM Amp
HS Amp, HS1,
CM21,
CM Amp
HS Amp, HS1,
CM21,
CM Amp
-65°C 3.40 1.5
Model Number Part
Number
Operating
Tempera-
ture
0.50
.425 dia.
Pin Circle
Background
Pins
Omitted
0.55 dia.
0.435
0.06
Dim. "A"
Sapphire
Window
Side View
0.690
.147 dia
2 holes
Cooler (+)
Cooler (-)
Thermistor pins
Bottom View
0.96 1.24
J12TE2-66S
0.12"
J12TE3-66S
0.07"
DIMENSION "A"
Detector(+)
Detector(-)
Side View
Detector(+)
Detector(-)
Bottom View
Cooler(+)
Cooler(-)
Thermistor
0.76
0.56
0.37
0.20 0.28
0.32
6 pins on .200"
bolt circle
0.5
Detector Plane
Background Pins
Omitted
Sapphire Window
.10 to
detector
plane
.10 dia
pin circle
Case(-)
(+)
.187
.110
.190
.50 (nom)
Case(-)
(+)
.326
.240
.07 to
detector
plane
.200
.50 (nom)
.20 dia
pin circle
J12 SERIES
INAS DETECTORS
Operating Instructions
• LD2 • 5AP • 18C
• 37S • 8B6 • 66S
P1
P2
P3
R3
RS
TC6 TEC
TEMPERATURE CONTROLLER
DETECTOR
ASSEMBLY
V
S
= +5 VOLTS
RT
TEC
DETECTOR
TEC MAXIMUM
CURRENT
ADJUSTMENT
CUSTOMER SELECTED
TEMPERATURE
SET RESISTOR
TEMP. SET RES. MONITOR
SIGNAL GND.
SIGNAL GND.
PWR. GND.
+5 VOLT SUPPLY
EXT. TEMP. SET RESISTOR
BRIDGE MONITOR
TEMP. STABILIZED IND.
TEC CUR. MONITOR
+5 VOLT REF.
+
<
<
>
>
S
19.99
POWER
SUPPLIES
P/I
CONTROLLER
POWER
DRIVER
CURRENT
LIMIT
J1
THERM
115/230 V
GAIN SET
THERM SET
THERM
SET SENSE
CURRENT
SENSE
CURRENT
LIMIT
SET
CURRENT
SET SENSE
THERMISTOR
SENSE THERMISTOR AMP
INT
SET
<
<
>
>
<
<
>
>
<
<
>
>
DETECTOR
J12 SERIES
INAS DETECTORS
Operating Instructions
Judson Technologies, LLC
Information in this document is believed to be reliable. However, no responsibility is assumed for possible inaccuracies or
omission. Specifications are subject to change without notice.
221 COMMERCE DRIVE
MONTGOMERYVILLE, PA 18936-9641
TEL: 215-368-6901 · FAX: 215-362-6107
WWW.JUDTECH.COM
Temperature Controllers
The Judson Model TC5 power supply and
temperature controller provides convenient cooler
operation at a range of fixed temperatures. The built-in
thermistor is used to stabilize the detector temperature.
To operate without automatic temperature
control, use a 2.5V power supply. Beginning with a fixed
voltage and low current, gradually increase the current
as the detector cools. The thermistor can be used to
monitor the detector temperature if desired.
Heat Sinking the Thermoelectric Cooler
Judson thermoelectric coolers dissipate up to 5 watts
of power. Heat sinking is necessary to dissipate this
power. Judson offers the following heat sinks to
accomplish this task.
HS1 Heat Sink for Judson 66S/66G Packages
The HS1 heat sink is available for Judson Ge, InAs and
HgCdTe TE cooled detectors mounted in the 66S and
66G packages. The heat sink is designed to provide
easy heat sinking to the customer’s bench top or
optical system.
HSA2 Heat Sink Assembly for Judson
Thermoelectrically Cooled Detectors
The HSA2 two-stage thermoelectric cooler and heat
sink assembly is available for Judson TE cooled
detectors. The assembly consists of the specified
detector, a thermistor and a two-stage thermoelectric
cooler mounted in a hermetic package with heat sink
and detachable cables. The Model TC5 temperature
controller is specifically designed for use with the
HSA2.
TC6 Miniature Temperature Controller
FEAFEA
FEAFEA
FEATURESTURES
TURESTURES
TURES
• Precise Temperature Control • T empera ture Sta bility to ±0.02°C
• Temperature Set with a Single Resistor • Single +5 Volt Power Supply Operation
• Operates with Most TEC Cooled Detectors • Thermistor Bridge Monitor
• LED Temperature Stabilization • TEC Current Monitor
• Maximum TEC Current Adjustable to 2 Amps • Small Size
• Detailed Instruction Manuat Provided
CAUTION:
Max. current for the TE2, TE3 and TE4 is 1.3 ampere.
Max. current for the TE1 is 1.0 ampere. When using a
one stage cooler, a series resistor needs to be installed
with the TC to limit the max. current to 1.0 ampere.
Typical Setup with TC5
Automatic Temperature Control
Package pin configurations:
See Product Outline Drawing supplied with detector.
Caution: Observe cooler polarity and max. power rating.
Detector Output
TE Cooler Power
and Thermistor
Cable length
15" nominal
Cable length
45" nominal
1.8
dia.
Threaded Bushing
7/8 - 28 UN Thread
1.0
dia.
Protective Cap
1.59 to
Detector
Plane
1.78 to Top
of Threaded
Bushing
2.03 ref.
.25
ref.
6 Bolt Holes
Equally Spaced
on 1.375 dia.
Front View
(Cap Removed)
1 2 3 4 5
6 7 8 9
Cooler - Pin 2
Cooler + Pin 4
Thermistor Pin 7
Thermistor Pin 8
220-012104
