ALPHA CDB7620-000

Silicon Schottky Diode Chips
Features
■ For Detector and Mixer Applications
■ Low Capacitance for Usage Beyond 40 GHz
■ ZBD and Low Barrier Designs
■ P-Type and N-Type Junctions
■ Large Bond Pad Chip Design
Description
In a detector circuit operating at zero bias, depending on
the video load impedance, a ZBD device with RV less than
10 kΩ may be more sensitive than a low barrier diode with
RV greater than 100 kΩ. Applying forward bias reduces
the diode video resistance as shown in Figure 2. Lower
video resistance also increases the video bandwidth but
does not increase voltage sensitivity, as shown in
Figure 3. Biased Schottky diodes have better temperature
stability and also may be used in temperature
compensated detector circuits.
Alpha’s product line of silicon Schottky diode chips are
intended for use as detector and mixer devices in hybrid
integrated circuits at frequencies from below 100 MHz to
higher than 40 GHz. Alpha’s “Universal Chip” design
features a 4 mil diameter bond pad that is offset from the
semiconductor junction preventing damage to the active
junction as a result of wire bonding.
As power-sensing detectors, these Schottky diode chips
all have the same voltage sensitivity so long as the output
video impedance is much higher than the video
resistance of the diode. Figure 1 shows the expected
detected voltage sensitivity as a function of RF source
impedance in an untuned circuit. Note that sensitivity is
substantially increased by transforming the source
impedance from 50 Ω to higher values. Maximum
sensitivity occurs when the source impedance equals the
video resistance.
P-type Schottky diodes generate lower 1/F noise and are
preferred for Doppler mixers and biased detector
applications. The bond pad for the P-type Schottky diode
is the cathode. N-type Schottky diodes have lower parasitic
resistance, RS, and will perform with lower conversion loss
in mixer circuits. The bond pad for the N-type Schottky
diode is the anode.
Electrical Specifications at 25°C
CJ1
(pF)
RT2
Ω)
(Ω
VF @ 1 mA
(mV)
VB3
(V)
RV @ Zero Bias
Ω)
(kΩ
Max.
Max.
Min.–Max.
Min.
Typ.
0.25
30
135–240
1
5.5
Part Number
Barrier
Junction
Type
CDC7630-000
ZBD
P
CDC7631-000
ZBD
P
0.15
80
150–300
2
7.2
526-006
CDB7619-000
Low
P
0.10
40
275–375
2
735
526-006
CDB7620-000
Low
P
0.15
30
250–350
2
537
526-006
CDF7621-000
Low
N
0.10
20
270–350
2
680
526-011
CDF7623-000
Low
N
0.30
10
240–300
2
245
526-011
Outline
Drawing
526-006
1. CJ for low barrier diodes specified at 0 V. CJ for ZBDs specified at 0.15 V
reverse bias.
2. RT is the slope resistance at 10 mA. RS Max. may be calculated from:
RS = RT - 2.6 x N.
3. VB for low barrier diodes is specified at 10 µA. VB for ZBDs is specified
at 100 µA.
Alpha Industries, Inc. [781] 935-5150 • Fax [617] 824-4579 • Email sales@alphaind.com • www.alphaind.com
Specifications subject to change without notice. 8/01A
1
Silicon Schottky Diode Chips
Typical Performance Data
Detected Voltage (mV)
10000
DETECTOR
VOLTAGE
RF SOURCE
IMPEDANCE
1000
PInput
RFC
VIDEO LOAD
IMPEDANCE
500 Ω
100
200 Ω
100 Ω
Zero Biased Detector
50 Ω
10
25 Ω
DETECTOR
VOLTAGE
1
RF SOURCE
IMPEDANCE
0.1
-40
-30
-20
-10
0
RFC
PInput
VIDEO LOAD
IMPEDANCE
10
Input Power (dBm)
Biased Detector
Figure 1. Detected Voltage vs. Input
Power and RF Source Impedance
10000
Detected Voltage (mV)
Video Resistance (Ω)
100000
Low Barrier
10000
ZBD
1000
100
1
10
+10 dBm
1000
100
10
1
-30 dBm
-20 dBm
0.1
-10dBm
0.01
0.001
0.001
100
0 dBm
0.01
0.1
1
10
Forward Current (mA)
Forward Bias (µA)
Figure 2. Video Resistance vs. Forward Bias Current
Figure 3. Detected Voltage vs. Forward Current
SPICE Model Parameters
2
Parameter
CDB7619
CDB7620
CDF7621
CDF7623
CDC7630
CDC7631
Units
IS
3.70E-08
5.40E-08
4.0E-08
1.1E-07
5.0E-06
3.8E-06
A
Ω
RS
9
14
12
6
20
51
N
1.05
1.12
1.05
1.04
1.05
1.05
TT
1E-11
1E-11
1E-11
1E-11
1E-11
1E-11
S
CJ0
0.08
0.15
0.10
0.22
0.14
0.08
pF
M
0.35
0.35
0.35
0.32
0.40
0.4
EG
0.69
0.69
0.69
0.69
0.69
0.69
XTI
2.0
2.0
2.0
2.0
2.0
2.0
FC
0.5
0.5
0.5
0.5
0.5
0.5
eV
BV
2.0
4.0
3.0
2.0
2.0
2.0
IBV
1.00E-05
1.00E-05
1.0E-05
1.0E-05
1.0E-04
1.0E-04
A
VJ
0.495
0.495
0.495
0.495
0.340
0.340
V
Alpha Industries, Inc. [781] 935-5150 • Fax [617] 824-4579 • Email sales@alphaind.com • www.alphaind.com
Specifications subject to change without notice. 8/01A
V
Silicon Schottky Diode Chips
Outline Drawing
Absolute Maximum Ratings
526-006, 526-011
Characteristic
0.015 (0.38 mm)
0.013 (0.33 mm)
0.015 (0.38 mm)
0.013 (0.33 mm)
Reverse Voltage (VR)
BONDING PAD
DIAMETER
0.0035 (0.089 mm)–
0.0045 (0.114 mm)
Value
Voltage Rating
Forward Current (IF)
50 mA
Power Dissipation (PD)
75 mW
Storage Temperature (TST)
-65°C to +150°C
Operating Temperature (TOP)
-65°C to +150°C
0.0085 (0.216 mm)
0.0065 (0.165 mm)
526-006 = Cathode bond pad.
526-011 = Anode bond pad.
Alpha Industries, Inc. [781] 935-5150 • Fax [617] 824-4579 • Email sales@alphaind.com • www.alphaind.com
Specifications subject to change without notice. 8/01A
3