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Features
Both P–Type and N–Type Low Barrier Silicon
Available
Low 1/f Noise
Bonded Junctions for Reliability
Planar Passivated Beam–Lead and Chip
Construction
See Also Zero Bias Silicon Schottky Barrier
Detector Diodes
Description
Alpha packaged, beam–lead and chip Schottky
barrier detector diodes are designed for applications
through 40 GHz in Ka–band. They are made by the
deposition of a suitable barrier metal on an epitaxial
silicon substrate to form the junction. The process
and choice of materials result in low series resistance
along with a narrow spread of capacitance values for
close impedance control. P–type silicon is used to
obtain superior 1/f noise characteristics. N–type
silicon is also available.
The packaged diodes are suitable for use in
waveguide, coaxial, and stripline applications.
The beam–lead and chip diodes can also be mounted
in a variety of packages or on special customer
substrates.
Unmounted beam–lead diodes are especially well
suited for use in MIC applications. Mounted
beam–lead diodes can be easily used in MIC,
stripline or other such circuitry.
The “Universal Chips” are designed for a high degree
of device reliability in both commercial and industrial
uses. The offset bond pad assures that no
mechanical damage will occur at the junction during
the wire bonding. Additionally the 4 mil bond pad
eliminates performance variation due to bonding and
is ideal for automated assembly, and improves
efficiency during manual operations as well.
The choice on “N” and “P” type silicon allows for the
designer to optimize the silicon material for the
intended application.
Doppler mixers, high sensitivity detectors will
benefit from using the low noise characteristics
of the “P” type silicon.
Low conversion loss mixers and biased
detectors can be designed using standard “N”
type material.
Silicon Schottky Barrier Detector Diodes
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Applications
These diodes are categorized by TSS (Tangential
Signal Sensitivity) for detector applications in four
frequency ranges: S, X, Ku, and Ka–band. However,
they can also be used as modulators, high speed
switches and low power limiters. RF parameters on
chips and beam–lead diodes are tested on a sample
basis, while breakdown voltage and capacitance
measurements are 100% tested. Packaged diodes
are 100% RF tested.
TSS is the one parameter that best describes a
diode’s use as a video detector. It is defined as the
amount of signal power, below a one milliwatt
reference level, required to produce an output pulse
whose amplitude is sufficient to raise the noise
fluctuations by an amount equal to the average noise
level. TSS is approximately 4 dB above the Minimum
Detectable Signal.
The Schottky barrier diodes in this data sheet are of
P–type construction and are optimized for low noise,
particularly in the 1/f region. They require a small
forward bias (to overcome the barrier potential) if
efficient operation is required, especially at power
levels below –20 dBm. Bias not only increases
sensitivity but also greatly reduces parameter
variation due to temperature change. Video
impedance is a direct function of bias and closely
follows the 28/l (mA) relationship. This is important
to pulse fidelity, since the video impedance in
conjunction with the detector output capacitance
affects the effective amplifier bandwidth.
Bias does, however, increase noise, particularly in
the 1/f region. Therefore, it should be kept at as low
a level as possible (typically 5–50 microamps).
Voltage output versus power input as a function of
load resistance and bias is shown in Figures 1a
and 1b.
Assembly and Handling Procedure
Die Attach Methods
All universal chips are compatible with both eutectic
and conductive epoxy die attach methods.
Eutectic composition preforms of Au/Sn or Au/Ge are
useful when soldering devices in circuit. Gold/silicon
eutectic die attach can be accomplished by scrubbing
the chip directly to the gold plated bonding area.
Epoxy die attach with silver or gold filled conductive
epoxies, can also be used where thermal heat sinking
is not a requirement.
Wire Bonding
T wo methods can be used to connect wire, ribbon, or
wire mesh to the chips:
Thermocompression
Ballbonding
Alpha recommends use of pure gold wire (0.7 – 1.25 mil
diameter).
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Electrical Specifications at 25
°
C
“P” Type Detectors
Beam–Lead
Electrical
Characteristics Test
Conditions
Frequency
Band
Part
Number
TSS –
dBm1,2 ZIF
(Ohms) Gamma
()CJ @ 0V
(pF) VF
@ 1 mA
(mv)
RT
@ 10 mA
(Ohms)
VB
@ 10 µA
(V)
Frequency
GHz
Outline
Drawing
Number
Band
Number
Min. Min. Max. Max.
(mv)
(Ohms)
(V)
Number
X
Ku
K
DDB2503–000
DDB2504–000
DDB2265–000
50
48
503
500
500
8003
700
700
12003
0.15
0.10
0.10
200–350
200–350
300–450
2
2
3
10
16
24.15
491–006
491–006
491–006
Chip
Ku
KCDB7620–000
CDB7619–000 40
503500
500 700
700 8000
5000 0.15
0.10 250–350
300–450 30
40 2
316
24.15 526–006
526–006
Packaged Diodes
Ku
K
X
Ku
K
K
CDB7620–207
CDB7619–207
DDB2503–250
DDB2504–250
DDB2265–250
DDB2265–220
40
50
50
48
503
503
500
500
500
500
8003
8003
700
700
700
700
12003
12003
8000
5000 0.15
0.10
0.15
0.10
0.10
0.10
300–350
300–450
200–350
200–350
300–450
300–450
30
40
40
40
2
3
2
2
3
3
16
24.15
10
16
24.15
24.15
207
207
250
250
250
220
“N” Type Detectors
Electrical Characteristics
Frequency
Band Part
Number Drive
Level VF
@ 1 mA
(mv)
CJ @ 0V
(pF) RT
@ 10 mA
(Ohms)
VB
@ 10 uA
(V)
(mv)
Max.
(Ohms)
(V)
X CDF7623–000 Low 240–300 0.30 10 2
K CDF7621–000 Low 270–350 0.10 20 2
Ku CME7660–000 Med 350–450 0.15 10 3
K CDE7618–000 Med 375–500 0.10 20 3
Ku CDP7624–000 Med/High 450–575 0.15 15 3
1. Bias = 50 µA.
2. Video Bandwidth = 10 MHz.
3. Bias = 30 µA.
4. RV = 2800 Ohms.
Silicon Schottky Barrier Detector Diodes
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Spice Model Parameters
Part Number
Parameter Unit CDF7621–000 CDC7630–000 CDB7619–000
ISA8E–08 3E–06 3E–09
RSOhm 6 26 26
n – 1.04 1.04 1.04
TDs 1E–11 1E–11 1E–11
CJ0 pF 0.11 0.1 0.11
m – 0.3 0.25 0.32
EGeV 0.69 0.69 0.69
VJ– 0.51 0.34 0.54
XTI – 2 2 2
FC – 0.5 0.5 0.5
BVV 2.5 2 3
IBV A 1E–05 0.001 1E–05
Typical I–V Characteristics
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
VF (Volts)
10–1
10–2
10–3
10–4
10–5
I (Amps)
F
10–6
CDF7621–000
10–1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
VF (Volts)
10–2
10–3
10–4
10–5
I (Amps)
F
10–6
CDC7630–000
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
VF (Volts)
10–1
10–2
10–3
10–4
10–5
I (Amps)
F
10–6
CDB7619–000
Shipping Information
Individual Chips
Standard packaging procedures at Alpha are for
“wafflepack” delivery. Devices can also be packaged
on “GelPack” carriers.
Wafer Shipment for Whole Wafer
Packaging options include delivery for devices on film
frame where wafer is sawn on wafer gel pack for
uncut, unsawn wafer.
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Typical Performance Data
RL = 1KΩ
RL = 10KΩ
0.10
1.00
10.00
100.00
1000.00
10000.00
–30 –20 –10 0 10 20
RL = 1Ω
RL = 10Ω
RL = 100Ω
RL = 100KΩ
RL = 1MΩ
Test Conditions:
F=9.375 GHz
DC Bias = 0
Power Input, dBm
Voltage Output, mV
Figure 1a. Voltage Output vs. Power Input as a
Function of Load Resistance
0.10
1.00
10.00
100.00
1000.00
10000.00
–30 –20 –10 0 10 20
Test Conditions:
F=9.375 GHz
Power Input, dBm
Voltage Output, mV
RL = 1KΩ
RL = 10Ω
5 µA
50 µA
5 µA
5 µA
50 µA
RL = 1MΩ
Figure 1b. Voltage Output vs. Power Input as a
Function of Load Resistance and Bias
Input Video Output
Load Resistor
DC Return
RF Bypass
a) Unbiased
Input Video Output
Load Resistor
DC Return
RF Bypass
a) Biased
Bias Supply
Multi Octave–High Sensitivity
Input Video Output
Load Resistor
RF Bypass
a) Unbiased
Input Video Output
Load Resistor
RF Bypass
a) Biased
Bias Supply
Broadband–Low Sensitivity
50Ω
Figure 2. Typical Video Detector Circuits
Frequency Table
Band Frequencies (GHz)
UHF
L
S
C
X
Ku
K
Ka
mm
Up to 1
1 – 2
2 – 4
4 – 8
8.2 – 12.4
12.4 – 18
18.0 – 26.5
26.5 – 40
40 – 100
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Outline Drawings
491–006 526–006, 526–011
0.015 (0.38 mm)
0.013 (0.33 mm)
0.015 (0.38 mm)
0.013 (0.33 mm)
Diameter 0.0035 – 0.00
4
Bonding Pad
(526–006 Cathode)
0.0085 (0.216 mm)
526–006 = Cathode Bond Pad
0.0065 (0.165 mm)
526–011 = Anode Bond Pad
526–011 Anode)
Silicon Schottky Barrier Detector Diodes
