TM
DATA SHEET
Silicon Schottky Barrier Diodes in Hermetic and Epoxy
Ceramic Packages
Applications
Detectors
Mixers
Features
Available in both P-type and N-type low barrier designs
Low 1/f noise
Packages rated MSL1, 260
C
per JEDEC J-STD-020
Description
The Isolink packaged Schottky barrier detector diodes are
designed for applications through 20 GHz in the 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.
Packaged diodes are suitable for use in waveguide, coaxial, and
stripline applications.
The choice of N- and P-type silicon allows the designer to
optimize the silicon material for the intended application:
Doppler mixers and high-sensitivity detectors 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.
The P-type Schottky diodes in this data sheet are optimized for
low noise in the 1/f region. They require a small forward bias (to
reduce video resistance) if efficient operation is required. The bias
not only increases sensitivity but also reduces parameter variation
due to temperature change. Video impedance is a direct function
of bias and follows the 26/l (mA) relationship. This is important to
pulse fidelity, since the video impedance together with the
detector output capacitance affects the effective amplifier
bandwidth.
Bias does, however, increase typical noise, particularly in the 1/f
region. Therefore, it should be kept as low as possible (typically 5
to 50
μA).
Electrical and physical specifications for the silicon Schottky
barrier diodes are provided in Tables 1 through 3. SPICE model
parameters are defined in Table 4. Typical I-V characteristics are
shown in Figures 1 and 2. Typical performance characteristics are
shown in Figures 3 and 4. Typical video detector circuits are
shown in Figure 5.
Applications
These diodes are categorized by Tangential Signal Sensitivity
(TSS) for detector applications in four frequency ranges: S, X, Ku,
and Ka bands. However, they can also be used as modulators,
high-speed switches, and low-power limiters.
TSS is a parameter that describes a diode’s detector sensitivity. It
is defined as the amount of signal power, below a one-milliwatt
reference level, required to produce an output pulse with an
amplitude 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.
Isolink, Inc. • Phone [408] 946-1968 • Fax [408] 946-1960 • sales@isolink.com • www.isolink.com
203258B • Isolink Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 1, 2015
1
SILICON SCHOTTKY BARRIER DIODES
Table 1. Electrical Specifications: Beam-Lead P-Type Detector Schottky Diodes (Note 1)
TSS
(dBm)
(Note 2)
Typical
DDB2503-220
DDB2503-230
DDB2503-250
DDB2504-220
DDB2504-230
DDB2504-250
DDB2265-220
DDB2265-230
DDB2265-250
Bias = 50 μA
Video bandwidth = 10 MHz.
Bias = 30 μA
Frequency
Band
X
X
X
Ku
Ku
Ku
K
K
K
Note 1:
Note 2:
Note 3:
Part Number
R
V
(Ω)
Minimum
500
500
500
500
500
500
800 (Note 3)
800 (Note 3)
800 (Note 3)
Maximum
700
700
700
700
700
700
1200 (Note 3)
1200 (Note 3)
1200 (Note 3)
Total
Capacitance (CT)
@0V
(pF)
Maximum
0.3
0.3
0.3
0.2
0.2
0.2
0.2
0.2
0.2
V
F
@ 1.0 mA
(mV)
Minimum
200
200
200
200
200
200
300
300
300
Maximum
350
350
350
350
350
350
450
450
450
V
B
@ 10 uA
(V)
Minimum
2
2
2
2
2
2
3
3
3
50
50
50
48
48
48
50 (Note3)
50 (Note3)
50 (Note3)
Performance is guaranteed only under the conditions listed in this table.
Table 2. Electrical Specifications: P-Type Detector Schottky Diodes (Note 1)
Total
Capacitance
(C
T
) @ 0 V
(pF)
Maximum
0.4
0.4
0.35
0.35
Total
Resistance (R
T
)
@ 10 mA
(Ω)
(Note 3)
Maximum
30
30
40
40
Frequency
Band
Ku
Ku
K
K
Note 1:
Note 2:
R
V
(Ω)
Part Number
CDB7620-203
CDB7620-207
CDB7619-203
CDB7619-207
Barrier
Low
Low
Low
Low
Typical
537
537
735
735
TSS
(dBm)
(Note 2)
Typical
+40
+40
+50 (Note 4)
+50 (Note 4)
V
F
@ 1 mA
(mV)
Minimum
250
250
275
275
Maximum
350
350
375
375
V
B
@ 10
μA
(V)
Minimum
2
2
3
3
Performance is guaranteed only under the conditions listed in this table.
Bias = 50 μA
Video bandwidth = 10 MHz
RV = 2800
Ω
R
t
is the slope resistance @ 10 mA. The maximum series resistance (R
S
) is calculated as : R
S
= R
t
– 2.8
Bias = 30 μA
Note 3:
Note 4:
Isolink, Inc. • Phone [408] 946-1968 • Fax [408] 946-1960 • sales@isolink.com • www.isolink.com
203258B • Isolink Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 1, 2015
2
DATA SHEET • SILICON SCHOTTKY BARRIER DIODES
Typical I-V Characteristics
10
–1
10
–2
10
–1
10
–2
Forward
Current
(A)
10
–3
10
–4
10
–5
10
–6
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Forward
Current
(A)
10
–3
10
–4
10
–5
10
–6
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Forward Voltage (V)
Figure 1. CDF7621
Forward Voltage (V)
Figure 2. CDB7619
Typical Performance Characteristics
10000.00
10000.00
R
L
= 10 kΩ
R
L
= 1 MΩ
R
L
= 1 kΩ
R
L
= 1 MΩ
R
L
= 1 kΩ
50
μA
Voltage Output (mV)
R
L
= 100 kΩ
R
L
= 100
Ω
Voltage Output (mV)
1000.00
100.00
R
L
= 10
Ω
1000.00
100.00
10.00
5
μA
5
μA
50
μA
R
L
= 10
Ω
10.00
R
L
= 1
Ω
1.00
0.10
–30
1.00
Test
Conditions:
f =
9.375 GHz
DC Bias = 0
5
μA
Test
Conditions:
f =
9.375 GHz
–20
–10
0
+10
+20
0.10
–30
–20
–10
0
+10
+20
Input Power (dBm)
Input Power (dBm)
Figure 3. Voltage Output vs Input Power as a Function of Load
Resistance
Figure 4. Voltage Output vs Input Power as a Function of Load
Resistance and Bias
Isolink, Inc. • Phone [408] 946-1968 • Fax [408] 946-1960 • sales@isolink.com • www.isolink.com
203258B • Isolink Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 1, 2015
4
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