HSMS-286B-BLKG [AVAGO]
HSMS-286x Series Surface Mount Microwave Schottky Detector Diodes; HSMS- 286x系列表面贴装肖特基微波检波二极管型号: | HSMS-286B-BLKG |
厂家: | AVAGO TECHNOLOGIES LIMITED |
描述: | HSMS-286x Series Surface Mount Microwave Schottky Detector Diodes |
文件: | 总18页 (文件大小:430K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
HSMS-286x Series
Surface Mount Microwave Schottky Detector Diodes
Data Sheet
Description
Features
• Surface Mount SOT‑23/SOT‑143 Packages
• Miniature SOT‑323 and SOT‑363 Packages
• High Detection Sensitivity:
up to 50 mV/µW at 915 MHz
up to 35 mV/µW at 2.45 GHz
up to 25 mV/µW at 5.80 GHz
Avago’s HSMS‑286x family of DC biased detector diodes
have been designed and optimized for use from 915 MHz
to 5.8 GHz.They are ideal for RF/ID and RFTag applications
as well as large signal detection, modulation, RF to DC
conversion or voltage doubling.
Available in various package configurations, this family
of detector diodes provides low cost solutions to a wide
variety of design problems. Avago’s manufacturing
techniques assure that when two or more diodes are
mounted into a single surface mount package, they
are taken from adjacent sites on the wafer, assuring the
highest possible degree of match.
• Low FIT (Failure in Time) Rate*
• Tape and Reel Options Available
• Unique Configurations in Surface Mount SOT‑363
Package
– increase flexibility
– save board space
– reduce cost
Pin Connections and Package Marking
• HSMS‑286K Grounded Center Leads Provide up to
1
2
3
6
5
4
10 dB Higher Isolation
• Matched Diodes for Consistent Performance
• Better Thermal Conductivity for Higher Power
Dissipation
• Lead‑free
Notes:
*
For more information see the Surface Mount Schottky Reliability
Data Sheet.
1. Package marking provides orientation and identification.
2. The first two characters are the package marking code.
The third character is the date code.
SOT-323 Package Lead Code Identification (top view)
SINGLE
3
SERIES
3
SOT-23/SOT-143 Package Lead Code Identification
(top view)
1
2
1
2
SINGLE
3
SERIES
3
B
C
COMMON
ANODE
3
COMMON
CATHODE
3
1
2
1
2
#0
#2
COMMON
ANODE
3
COMMON
CATHODE
3
1
2
1
2
F
E
SOT-363 Package Lead Code Identification (top view)
1
2
1
2
#4
#3
HIGH ISOLATION
UNCONNECTED
TRIO
NCONNECTED PAIR
UNCONNECTED
PAIR
6
1
6
1
5
4
6
1
6
1
5
4
3
4
2
3
2
3
L
1
2
K
#5
BRIDGE
QUAD
RING
QUAD
5
4
5
4
2
3
2
3
P
R
SOT-23/SOT-143 DC Electrical Specifications, TC = +25°C, Single Diode
Part
Number
HSMS-
Package
Marking
Code
Typical
Capacitance
CT (pF)
Lead
Code
Forward Voltage
VF (mV)
Configuration
2860
2862
2863
2864
2865
T0
T2
T3
T4
T5
0
2
3
4
5
Single
Series Pair[1,2]
Common Anode[1,2]
Common Cathode[1,2]
Unconnected Pair [1,2]
250 Min.
350 Max.
0.30
Test Conditions
IF = 1.0 mA
VR = 0 V, f = 1 MHz
Notes:
1. ∆VF for diodes in pairs is 15.0 mV maximum at 1.0 mA.
2. ∆CT for diodes in pairs is 0.05 pF maximum at –0.5V.
SOT-323/SOT-363 DC Electrical Specifications, TC = +25°C, Single Diode
Part
Number
HSMS-
Package
Marking
Code
Typical
Capacitance
CT (pF)
Lead
Code
Forward Voltage
VF (mV)
Configuration
286B
286C
286E
286F
286K
T0
T2
T3
T4
TK
B
C
E
F
K
Single
Series Pair[1,2]
Common Anode[1,2]
Common Cathode[1,2]
High Isolation
250 Min.
350 Max.
0.25
Unconnected Pair
Unconnected Trio
Bridge Quad
286L
286P
286R
TL
TP
ZZ
L
P
R
Ring Quad
Test Conditions
IF = 1.0 mA
VR = 0 V, f = 1 MHz
Notes:
1. ∆VF for diodes in pairs is 15.0 mV maximum at 1.0 mA.
2. ∆CT for diodes in pairs is 0.05 pF maximum at –0.5V.
2
RF Electrical Specifications, TC = +25°C, Single Diode
Part
Number
HSMS-
Typical Tangential Sensitivity
TSS (dBm) @ f =
Typical Voltage Sensitivity g
(mV/µW) @ f =
Typical Video
Resistance
RV (KΩ)
915 MHz
2.45 GHz
5.8 GHz
915 MHz
2.45 GHz
5.8 GHz
2860
2862
2863
2864
2865
286B
286C
286E
286F
286K
286L
286P
286R
–57
–56
–55
50
35
25
5.0
Test
Conditions
Video Bandwidth = 2 MHz
Ib = 5 µA
Power in = –40 dBm
RL = 100 KΩ, Ib = 5 µA
Ib = 5 µA
Attention:
Absolute Maximum Ratings, TC = +25°C, Single Diode
Observe precautions for
handling electrostatic
sensitive devices.
Symbol
Parameter
Unit
Absolute Maximum[1]
SOT-23/143 SOT-323/363
PIV
TJ
Peak Inverse Voltage
Junction Temperature
Storage Temperature
Operating Temperature
Thermal Resistance[2]
V
°C
4.0
4.0
ESD Machine Model (Class A)
150
150
TSTG
TOP
θjc
°C
‑65 to 150
‑65 to 150
500
‑65 to 150
‑65 to 150
150
ESD Human Body Model (Class 0)
°C
Refer to Avago Application Note A004R: Electro-
static Discharge Damage and Control.
°C/W
Notes:
1. Operation in excess of any one of these conditions may result in permanent damage to the
device.
2. TC = +25°C, where TC is defined to be the temperature at the package pins where contact is
made to the circuit board.
3
Equivalent Linear Circuit Model, Diode chip
SPICE Parameters
Parameter
Units
V
Value
7.0
R
j
BV
CJ0
pF
eV
A
0.18
0.69
1 E ‑ 5
5 E ‑ 8
1.08
6.0
R
S
EG
IBV
IS
A
N
C
j
RS
Ω
V
RS = series resistance (see Table of SPICE parameters)
Cj = junction capacitance (see Table of SPICE parameters)
PB (VJ)
PT (XTI)
M
0.65
2
8.33 X 10-5 nT
0.5
Rj =
Ib + Is
where
Ib = externally applied bias current in amps
Is = saturation current (see table of SPICE parameters)
T = temperature, °K
n = ideality factor (see table of SPICE parameters)
Note:
To effectively model the packaged HSMS-286x product,
please refer to Application Note AN1124.
4
Typical Parameters, Single Diode
10000
1000
100
100
10
1
10
100
R
= 100 KΩ
L
I (left scale)
F
T
T
T
= –55°C
= +25°C
= +85°C
A
A
A
2.45 GHz
10
1
915 MHz
10
.1
V (right scale)
5.8 GHz
F
1
DIODES TESTED IN FIXED-TUNED
FR4 MICROSTRIP CIRCUITS.
0.1
.01
1
-50
-40
-30
-2 0
-1 0
0
0.1 0.2 0.3 0.4 0.5 0.6 0. 7 0.8 0.9 1.0
FORWARD VOLTAGE (V)
0.05
0.10
0.15
0.20
0.25
FORWARD VOLTAGE (V)
POWER IN (dBm)
30
40
35
10,000
R = 100 KΩ
L
20 µA
5 µA
915 MHz
10 µA
10
1000
100
30
25
2.45 GHz
20
15
10
5
Frequency = 2.45 GHz
Fixed-tuned FR4 circuit
Input Power =
5.8 GHz
–30 dBm @ 2.45 GHz
Data taken in fixed-tuned
FR4 circuit
1
10
1
R
= 100 KΩ
L
DIODES TESTED IN FIXED-TUNED
FR4 MICROSTRIP CIRCUITS.
R
= 100 KΩ
L
0.3
-50
-40
-30
–40
–30
–20
–10
0
10
.1
1
10
100
BIAS CURRENT (µA)
POWER IN (dBm)
POWER IN (dBm)
5
The Height of the Schottky Barrier
Applications Information
Introduction
The current‑voltage characteristic of a Schottky barrier
diode at room temperature is described by the following
equation:
Avago’s HSMS‑286x family of Schottky detector diodes
has been developed specifically for low cost, high
volume designs in two kinds of applications. In small
signal detector applications (Pin < ‑20 dBm), this diode is
used with DC bias at frequencies above 1.5 GHz. At lower
frequencies, the zero bias HSMS‑285x family should be
considered.
V - IR
S
I = I S (exp
(
)
- 1)
0.026
On a semi‑log plot (as shown in the Avago catalog) the
current graph will be a straight line with inverse slope
2.3 X 0.026 = 0.060 volts per cycle (until the effect of RS is
seen in a curve that droops at high current). All Schottky
diode curves have the same slope, but not necessar‑
ily the same value of current for a given voltage. This is
determined by the saturation current, IS, and is related to
the barrier height of the diode.
In large signal power or gain control applications
(Pin> ‑20 dBm), this family is used without bias at
frequencies above 4 GHz. At lower frequencies, the
HSMS‑282x family is preferred.
Schottky Barrier Diode Characteristics
Through the choice of p‑type or n‑type silicon, and the
selection of metal, one can tailor the characteristics of a
Schottky diode. Barrier height will be altered, and at the
same time CJ and RS will be changed. In general, very
low barrier height diodes (with high values of IS, suitable
for zero bias applications) are realized on p‑type silicon.
Such diodes suffer from higher values of RS than do
the n‑type. Thus, p‑type diodes are generally reserved
for small signal detector applications (where very high
values of RV swamp out high RS) and n‑type diodes are
used for mixer applications (where high L.O. drive levels
keep RV low) and DC biased detectors.
Stripped of its package, a Schottky barrier diode chip
consists of a metal‑semiconductor barrier formed by
deposition of a metal layer on a semiconductor. The most
common of several different types, the passivated diode,
is shown in Figure 7, along with its equivalent circuit.
R
S
METAL
PASSIVATION
PASSIVATION
N-TYPE OR P-TYPE EPI LAYER
R
j
SCHOTTKY JUNCTION
C
j
N-TYPE OR P-TYPE SILICON SUBSTRATE
CROSS-SECTION OF SCHOTTKY
BARRIER DIODE CHIP
EQUIVALENT
CIRCUIT
Measuring Diode Linear Parameters
Figure 7. Schottky Diode Chip.
The measurement of the many elements which make
up the equivalent circuit for a packaged Schottky diode
is a complex task. Various techniques are used for each
element. The task begins with the elements of the diode
chip itself. (See Figure 8).
RS is the parasitic series resistance of the diode, the sum
of the bondwire and leadframe resistance, the resistance
of the bulk layer of silicon, etc. RF energy coupled into
RS is lost as heat—it does not contribute to the rectified
output of the diode. CJ is parasitic junction capacitance
of the diode, controlled by the thickness of the epitaxial
layer and the diameter of the Schottky contact. Rj is the
junction resistance of the diode, a function of the total
current flowing through it.
R
V
R
S
C
j
8.33 X 10 -5 n T
Figure 8. Equivalent Circuit of a Schottky Diode Chip.
R j =
= R V - R
s
I + I b
S
RS is perhaps the easiest to measure accurately. The V‑I
curve is measured for the diode under forward bias, and
the slope of the curve is taken at some relatively high
value of current (such as 5 mA). This slope is converted
into a resistance Rd.
0.026
=
at 25°C
I S + I b
where
n = ideality factor (see table of SPICE parameters)
T = temperature in °K
IS = saturation current (see table of SPICE parameters)
Ib = externally applied bias current in amps
0.026
If
R S = R d -
For n‑type diodes with relatively low values of saturation
current, Cj is obtained by measuring the total capaci‑
tance (see AN1124). Rj, the junction resistance, is calcu‑
lated using the equation given above.
IS is a function of diode barrier height, and can range
from picoamps for high barrier diodes to as much as 5
µA for very low barrier diodes.
6
The characterization of the surface mount package is
too complex to describe here—linear equivalent circuits
can be found in AN1124.
The situation is somewhat more complicated in the
design of the RF impedance matching network, which
includes the package inductance and capacitance
(which can be tuned out), the series resistance, the
junction capacitance and the video resistance. Of the
elements of the diode’s equivalent circuit, the parasitics
are constants and the video resistance is a function of
the current flowing through the diode.
Detector Circuits (small signal)
When DC bias is available, Schottky diode detector
circuits can be used to create low cost RF and
microwave receivers with a sensitivity of ‑55 dBm to
‑57 dBm.[1] Moreover, since external DC bias sets the
video impedance of such circuits, they display classic
square law response over a wide range of input power
levels[2,3]. These circuits can take a variety of forms, but
in the most simple case they appear as shown in Figure
9. This is the basic detector circuit used with the HSMS‑
286x family of diodes.
R V = R j + R S
The sum of saturation current and bias current sets
the detection sensitivity, video resistance and input RF
impedance of the Schottky detector diode. Where bias
current is used, some tradeoff in sensitivity and square
law dynamic range is seen, as shown in Figure 5 and
described in reference [3]
.
Output voltage can be virtually doubled and input
impedance (normally very high) can be halved through
The most difficult part of the design of a detector circuit
is the input impedance matching network. For very
broadband detectors, a shunt 60 Ω resistor will give good
input match, but at the expense of detection sensitivity.
the use of the voltage doubler circuit[4]
.
In the design of such detector circuits, the starting point
is the equivalent circuit of the diode. Of interest in the
design of the video portion of the circuit is the diode’s
video impedance—the other elements of the equiv‑
alent circuit disappear at all reasonable video frequen‑
cies. In general, the lower the diode’s video impedance,
the better the design.
When maximum sensitivity is required over a narrow
band of frequencies, a reactive matching network is
optimum. Such networks can be realized in either lumped
or distributed elements, depending upon frequency,
size constraints and cost limitations, but certain general
design principals exist for all types.[5] Design work begins
with the RF impedance of the HSMS‑286x series when
bias current is set to 3 µA. See Figure 10.
DC BIAS
L
1
Z-MATCH
NETWORK
VIDEO
OUT
RF
IN
5
2
DC BIAS
0.2
0.6
1
1 GHz
L
1
2
Z-MATCH
NETWORK
VIDEO
OUT
RF
IN
3
4
5
6
Figure 10. RF Impedance of the Diode.
Figure 9. Basic Detector Circuits.
[1]
Avago Application Note 923, Schottky Barrier Diode Video
Detectors.
[2] Avago Application Note 986, Square Law and Linear Detection.
[3] Avago Application Note 956‑5, Dynamic Range Extension of Schottky
Detectors.
[4] Avago Application Note 956‑4, Schottky Diode Voltage Doubler.
[5]
Avago Application Note 963, Impedance Matching Techniques for
Mixers and Detectors.
7
The HSMS‑282x family is a better choice for 915 MHz ap‑
plications—the foregoing discussion of a design using
the HSMS‑286B is offered only to illustrate a design
approach for technique.
915 MHz Detector Circuit
Figure 11 illustrates a simple impedance matching network
for a 915 MHz detector.
65nH
RF
INPUT
VIDEO
OUT
RF
INPUT
VIDEO
OUT
WIDTH = 0.017"
WIDTH = 0.050"
LENGTH = 0.436"
LENGTH = 0.065"
100 pF
100 pF
WIDTH = 0.078"
LENGTH = 0.165"
WIDTH = 0.015"
LENGTH = 0.600"
TRANSMISSION LINE
DIMENSIONS ARE FOR
MICROSTRIP ON
TRANSMISSION LINE
DIMENSIONS ARE FOR
MICROSTRIP ON
0.032" THICK FR-4.
0.032" THICK FR-4.
Figure 14. 2.45 GHz Matching Network.
Figure 11. 915 MHz Matching Network for the HSMS-286x Series at 3 µA Bias.
A 65 nH inductor rotates the impedance of the diode to
a point on the Smith Chart where a shunt inductor can
pull it up to the center. The short length of 0.065” wide
microstrip line is used to mount the lead of the diode’s
SOT‑323 package. A shorted shunt stub of length <λ/4
provides the necessary shunt inductance and simul‑
taneously provides the return circuit for the current
generated in the diode. The impedance of this circuit is
given in Figure12.
0.094" THROUGH, 4 PLACES
FINISHED
BOARD
SIZE IS
1.00" X 1.00".
MATERIAL IS
1/32" FR-4
EPOXY/
FIBERGLASS,
1 OZ. COPPER
BOTH SIDES.
0.030" PLATED THROUGH HOLE,
3 PLACES
Figure 15. Physical Realization.
2.45 GHz Detector Circuit
At 2.45 GHz, the RF impedance is closer to the line of
constant susceptance which passes through the center
of the chart, resulting in a design which is realized
entirely in distributed elements — see Figure 14.
FREQUENCY (GHz): 0.9-0.93
In order to save cost (at the expense of having a larger
circuit), an open circuit shunt stub could be substituted
for the chip capacitor. On the other hand, if space is at a
premium, the long series transmission line at the input
to the diode can be replaced with a lumped inductor. A
possible physical realization of such a network is shown
in Figure 15, a demo board is available from Avago.
Figure 12. Input Impedance.
The input match, expressed in terms of return loss, is
given in Figure 13.
0
-5
HSMS-2860
-10
-15
-20
RF IN
VIDEO OUT
0.9
0.915
0.93
CHIP CAPACITOR, 20 TO 100 pF
FREQUENCY (GHz)
Figure 16. Test Detector.
Figure 13. Input Return Loss.
As can be seen, the band over which a good match is
achieved is more than adequate for 915 MHz RFID ap‑
plications.
8
Two SMA connectors (E.F. Johnson 142‑0701‑631 or
equivalent), a high‑Q capacitor (ATC 100A101MCA50 or
equivalent), miscellaneous hardware and an HSMS‑286B
are added to create the test circuit shown in Figure 16.
The calculated input impedance for this network is
shown in Figure 17.
2.45 GHz
FREQUENCY (GHz): 2.3-2.6
Figure 19. Input Impedance. Modified 2.45 GHz Circuit.
This does indeed result in a very good match at midband,
as shown in Figure 20.
0
FREQUENCY (GHz): 2.3-2.6
-5
Figure 17. Input Impedance, 3 µA Bias.
The corresponding input match is shown in Figure 18. As
was the case with the lower frequency design, bandwidth
is more than adequate for the intended RFID application.
-10
-15
-20
0
-5
2.3
2.45
2.6
FREQUENCY (GHz)
-10
-15
-20
Figure 20. Input Return Loss. Modified 2.45 GHz Circuit.
However, bandwidth is narrower and the designer runs
the risk of a shift in the midband frequency of his circuit
if there is any small deviation in circuit board or diode
characteristics due to lot‑to‑lot variation or change in
temper‑ature. The matching technique illustrated in
Figure 17 is much less sensitive to changes in diode and
circuit board processing.
2.3
2.45
2.6
FREQUENCY (GHz)
Figure 18. Input Return Loss, 3 µA Bias.
A word of caution to the designer is in order. A glance
at Figure 17 will reveal the fact that the circuit does
not provide the optimum impedance to the diode at
2.45 GHz. The temptation will be to adjust the circuit
elements to achieve an ideal single frequency match, as
illustrated in Figure 19.
5.8 GHz Detector Circuit
A possible design for a 5.8 GHz detector is given in Figure
21.
RF
INPUT
VIDEO
OUT
WIDTH = 0.016"
LENGTH = 0.037"
20 pF
WIDTH = 0.045"
LENGTH = 0.073"
Figure 21. 5.8 GHz Matching Network for the HSMS-286x Series at 3 µA Bias.
9
As was the case at 2.45 GHz, the circuit is entirely dis‑ Such a circuit offers several advantages. First the voltage
tributed element, both low cost and compact. Input outputs of two diodes are added in series, increasing
impedance for this network is given in Figure 22.
the overall value of voltage sensitivity for the network
(compared to a single diode detector). Second, the RF
impedances of the two diodes are added in parallel,
making the job of reactive matching a bit easier. Such a
circuit can easily be realized using the two series diodes
in the HSMS‑286C.
The “Virtual Battery”
The voltage doubler can be used as a virtual battery,
to provide power for the operation of an I.C. or a tran‑
sistor oscillator in a tag. Illuminated by the CW signal
from a reader or interrogator, the Schottky circuit will
produce power sufficient to operate an I.C. or to charge
up a capacitor for a burst transmission from an oscilla‑
tor. Where such virtual batteries are employed, the bulk,
cost, and limited lifetime of a battery are eliminated.
FREQUENCY (GHz): 5.6-6.0
Figure 22. Input Impedance.
Temperature Compensation
Input return loss, shown in Figure 23, exhibits wideband
match.
The compression of the detector’s transfer curve is
beyond the scope of this data sheet, but some general
comments can be made. As was given earlier, the diode’s
video resistance is given by
0
-5
8.33 x 10‑5 nT
RV =
IS + Ib
-10
-15
-20
where T is the diode’s temperature in °K.
As can be seen, temperature has a strong effect upon RV,
and this will in turn affect video bandwidth and input
RF impedance. A glance at Figure 6 suggests that the
proper choice of bias current in the HSMS‑286x series
can minimize variation over temperature.
5.6
5.7
5.8
5.9
6.0
FREQUENCY (GHz)
Figure 23. Input Return Loss.
The detector circuits described earlier were tested
over temperature. The 915 MHz voltage doubler using
the HSMS‑286C series produced the output voltages
as shown in Figure 25. The use of 3 µA of bias resulted
in the highest voltage sensitivity, but at the cost of a
wide variation over temperature. Dropping the bias to
1 µA produced a detector with much less temperature
variation.
Voltage Doublers
To this point, we have restricted our discussion to
single diode detectors. A glance at Figure 9, however,
will lead to the suggestion that the two types of single
diode detectors be combined into a two diode voltage
doubler[4] (known also as a full wave rectifier). Such a
detector is shown in Figure 24.
A similar experiment was conducted with the HSMS‑
286B series in the 5.8 GHz detector. Once again, reducing
the bias to some level under 3 µA stabilized the output
of the detector over a wide temperature range.
Z-MATCH
NETWORK
VIDEO OUT
RF IN
It should be noted that curves such as those given in
Figures 25 and 26 are highly dependent upon the exact
design of the input impedance matching network. The
designer will have to experiment with bias current using
his specific design.
Figure 24. Voltage Doubler Circuit.
10
in a single package, such as the SOT‑143 HSMS‑2865 as
shown in Figure 29.
120
100
80
INPUT POWER = –30 dBm
3.0 µA
In high power differential detectors, RF coupling from
the detector diode to the reference diode produces a
rectified voltage in the latter, resulting in errors.
1.0 µA
10 µA
Isolation between the two diodes can be obtained
by using the HSMS‑286K diode with leads 2 and 5
grounded. The difference between this product and the
conventional HSMS‑2865 can be seen in Figure 29.
60
40
0.5 µA
-55 -35 -15
5
25 45
C)
65 85
3
4
6
5
4
TEMPERATURE (
°
Figure 25. Output Voltage vs. Temperature and Bias Current
in the 915 MHz Voltage Doubler using the HSMS-286C.
35
INPUT POWER = –30 dBm
1
2
1
2
3
3.0 µA
HSMS-286K
SOT-363
HSMS-2865
SOT-143
25
10 µA
Figure 29. Comparing Two Diodes.
1.0 µA
The HSMS‑286K, with leads 2 and 5 grounded, offers
some isolation from RF coupling between the diodes.
This product is used in a differential detector as shown
in Figure 30.
15
5
0.5 µA
-55 -35 -15
5
25 45
C)
65 85
detector
diode
PA
Vs
TEMPERATURE (
°
Figure 26. Output Voltage vs. Temperature and Bias Current
in the 5.80 GHz Voltage Detector using the HSMS-286B Schottky.
to differential
amplifier
Six Lead Circuits
HSMS-286K
reference diode
The differential detector is often used to provide temper‑
ature compensation for a Schottky detector, as shown in
Figures 27 and 28.
Figure 30. High Isolation Differential Detector.
In order to achieve the maximum isolation, the designer
must take care to minimize the distance from leads 2
and 5 and their respective ground via holes.
bias
Tests were run on the HSMS‑282K and the conventional
HSMS‑2825 pair, which compare with each other in the
same way as the HSMS‑2865 and HSMS‑286K, with the
results shown in Figure 31.
matching
network
differential
amplifier
Frequency = 900 MHz
5000
RF diode
V
out
1000
100
10
Figure 27. Differential Detector.
Square law
response
detector
PA
V
s
diode
HSMS-2825
ref. diode
to differential
amplifier
37 dB
47 dB
HSMS-282K
ref. diode
1
HSMS-2865
reference diode
0.5
-35
-25
-15
-5
5
15
INPUT POWER (dBm)
Figure 28. Conventional Differential Detector.
Figure 31. Comparing HSMS-282K with HSMS-2825.
These circuits depend upon the use of two diodes
having matched Vf characteristics over all operating
temperatures. This is best achieved by using two diodes
11
The line marked “RF diode, Vout” is the transfer curve for
the detector diode—both the HSMS‑2825 and the HSMS‑
282K exhibited the same output voltage. The data were
taken over the 50 dB dynamic range shown. To the right
is the output voltage (transfer) curve for the reference
diode of the HSMS‑2825, showing 37 dB of isolation. To
the right of that is the output voltage due to RF leakage
for the reference diode of the HSMS‑282K, demonstrating
10 dB higher isolation than the conventional part.
PRF = RF power dissipated
Note that θjc, the thermal resistance from diode junction
to the foot of the leads, is the sum of two component
resistances,
θjc = θpkg + θchip
Equation (2).
Package thermal resistance for the SOT‑323 and SOT‑363
package is approximately 100°C/W, and the chip thermal
resistance for these three families of diodes is approxi‑
mately 40°C/W. The designer will have to add in the
thermal resistance from diode case to ambient—a poor
choice of circuit board material or heat sink design can
make this number very high.
Such differential detector circuits generally use single
diode detectors, either series or shunt mounted diodes.
The voltage doubler offers the advantage of twice
the output voltage for a given input power. The two
concepts can be combined into the differential voltage
doubler, as shown in Figure 32.
bias
Equation (1) would be straightforward to solve but
for the fact that diode forward voltage is a function of
temperature as well as forward current. The equation,
equation 3, for Vf is:
differential
amplifier
11600 (V f - I f R s)
Equation (3).
nT
matching
network
If = I S
e
- 1
where
Figure 32. Differential Voltage Doubler, HSMS-286P.
n = ideality factor
Here, all four diodes of the HSMS‑286P are matched in
their Vf characteristics, because they came from adjacent
sites on the wafer. A similar circuit can be realized using
the HSMS‑286R ring quad.
T = temperature in °K
Rs = diode series resistance
and IS (diode saturation current) is given by
Other configurations of six lead Schottky products can
be used to solve circuit design problems while saving
space and cost.
2
n
1
T
1
298
- 4060
(
-
)
Equation (4).
T
Is = I 0
e
)
(
298
Thermal Considerations
The obvious advantage of the SOT‑363 over the SOT‑
Equations (1) and (3) are solved simultaneously to obtain
143 is combination of smaller size and two extra leads. the value of junction temperature for given values of
However, the copper leadframe in the SOT‑323 and SOT‑
diode case temperature, DC power dissipation and RF
363 has a thermal conductivity four times higher than power dissipation.
the Alloy 42 leadframe of the SOT‑23 and SOT‑143, which
enables it to dissipate more power.
The maximum junction temperature for these three
families of Schottky diodes is 150°C under all operating
conditions. The following equation, equation 1, applies
to the thermal analysis of diodes:
T j = (V I f + P RF ) θjc + Ta
Equation (1).
f
where
Tj = junction temperature
Ta = diode case temperature
θ
jc = thermal resistance
Vf If = DC power dissipated
12
Diode Burnout
Assembly Instructions
SOT-323 PCB Footprint
Any Schottky junction, be it an RF diode or the gate of
a MESFET, is relatively delicate and can be burned out
with excessive RF power. Many crystal video receivers
used in RFID (tag) applications find themselves in poorly
controlled environments where high power sources may
be present. Examples are the areas around airport and
FAA radars, nearby ham radio operators, the vicinity of
a broadcast band transmitter, etc. In such environments,
the Schottky diodes of the receiver can be protected by
a device known as a limiter diode.[6] Formerly available
only in radar warning receivers and other high cost
electronic warfare applications, these diodes have been
adapted to commercial and consumer circuits.
A recommended PCB pad layout for the miniature SOT‑
323 (SC‑70) package is shown in Figure 33 (dimensions
are in inches).
0.026
0.079
0.039
0.022
Avago offers a complete line of surface mountable PIN
limiter diodes. Most notably, our HSMP‑4820 (SOT‑23)
or HSMP‑482B (SOT‑323) can act as a very fast (nano‑
second) power‑sensitive switch when placed between
the antenna and the Schottky diode, shorting out the
RF circuit temporarily and reflecting the excessive RF
energy back out the antenna.
Dimensions in inches
Figure 33. Recommended PCB Pad Layout for Avago’s SC70 3L/SOT-323
Products.
A recommended PCB pad layout for the miniature
SOT‑363 (SC‑70 6 lead) package is shown in Figure 34
(dimensions are in inches). This layout provides ample
allowance for package placement by automated
assemblyequipmentwithoutaddingparasiticsthatcould
impair the performance.
0.026
0.075
0.035
0.016
Figure 34. Recommended PCB Pad Layout for Avago’s SC70 6L/SOT-363
Products.
[6] Avago Application Note 1050, Low Cost, Surface Mount Power Limiters.
13
SMT Assembly
zones. The preheat zones increase the temperature of
the board and components to prevent thermal shock
and begin evaporating solvents from the solder paste.
The reflow zone briefly elevates the temperature suffi‑
ciently to produce a reflow of the solder.
Reliable assembly of surface mount components is a
complex process that involves many material, process,
and equipment factors, including: method of heating
(e.g., IR or vapor phase reflow, wave soldering, etc.)
circuit board material, conductor thickness and pattern,
type of solder alloy, and the thermal conductivity and
thermal mass of components. Components with a low
mass, such as the SOT packages, will reach solder reflow
temperatures faster than those with a greater mass.
The rates of change of temperature for the ramp‑up and
cool‑down zones are chosen to be low enough to not
cause deformation of the board or damage to compo‑
nents due to thermal shock. The maximum temperature
in the reflow zone (TMAX) should not exceed 260°C.
Avago’s diodes have been qualified to the time‑tem‑
perature profile shown in Figure 35. This profile is repre‑
sentative of an IR reflow type of surface mount assembly
process.
These parameters are typical for a surface mount assembly
process for Avago diodes. As a general guideline, the circuit
board and components should be exposed only to the
minimum temperatures and times necessary to achieve a
uniform reflow of solder.
After ramping up from room temperature, the circuit
board with components attached to it (held in place
with solder paste) passes through one or more preheat
tp
Critical Zone
Tp
T
to Tp
L
Ramp-up
T
L
tL
Ts
max
Ts
min
Ramp-down
ts
Preheat
25
t 25° C to Peak
Time
Figure 35. Surface Mount Assembly Profile.
Lead-Free Reflow Profile Recommendation (IPC/JEDEC J-STD-020C)
Reflow Parameter
Lead-Free Assembly
3°C/ second max
150°C
Average ramp‑up rate (Liquidus Temperature (TS(max) to Peak)
Preheat
Temperature Min (TS(min))
Temperature Max (TS(max)
)
200°C
Time (min to max) (tS)
60‑180 seconds
3°C/second max
217°C
Ts(max) to TL Ramp‑up Rate
Time maintained above:
Temperature (TL)
Time (tL)
60‑150 seconds
260 +0/‑5°C
Peak Temperature (TP)
Time within 5 °C of actual Peak temperature (tP)
Ramp‑down Rate
20‑40 seconds
6°C/second max
8 minutes max
Time 25 °C to Peak Temperature
Note 1: All temperatures refer to topside of the package, measured on the package body surface
14
Package Dimensions
Outline 23 (SOT-23)
Outline SOT-323 (SC-70 3 Lead)
e1
e2
e1
E1
E
XXX
E1
E
XXX
e
L
B
e
C
L
D
DIMENSIONS (mm)
B
D
C
SYMBOL
MIN.
0.80
0.00
0.15
0.08
1.80
1.10
MAX.
1.00
0.10
0.40
0.25
2.25
1.40
A
A1
B
C
D
E1
e
e1
E
DIMENSIONS (mm)
A
SYMBOL
MIN.
0.79
0.000
0.30
0.08
2.73
1.15
0.89
1.78
0.45
2.10
0.45
MAX.
1.20
0.100
0.54
0.20
3.13
1.50
1.02
2.04
0.60
2.70
0.69
A
A1
B
C
D
E1
e
e1
e2
E
A1
A
0.65 typical
1.30 typical
Notes:
A1
1.80
0.26
2.40
0.46
XXX-package marking
Drawings are not to scale
L
Notes:
XXX-package marking
Drawings are not to scale
L
Outline 143 (SOT-143)
Outline SOT-363 (SC-70 6 Lead)
e2
e1
HE
E
B1
L
E
E1
XXX
e
c
D
DIMENSIONS (mm)
L
SYMBOL
E
D
HE
A
A2
A1
e
MIN.
1.15
1.80
1.80
0.80
0.80
0.00
MAX.
1.35
2.25
2.40
1.10
1.00
0.10
B
C
e
A1
A2
A
DIMENSIONS (mm)
D
SYMBOL
MIN.
0.79
0.013
0.36
0.76
0.086
2.80
1.20
0.89
1.78
0.45
2.10
0.45
MAX.
1.097
0.10
0.54
0.92
0.152
3.06
1.40
1.02
2.04
0.60
2.65
0.69
0.650 BCS
A
A1
B
b
c
L
0.15
0.08
0.10
0.30
0.25
0.46
b
A
B1
C
A1
D
E1
e
e1
e2
E
Notes:
XXX-package marking
Drawings are not to scale
L
15
Device Orientation
For Outlines SOT-23, -323
REEL
TOP VIEW
4 mm
END VIEW
8 mm
CARRIER
TAPE
ABC
ABC
ABC
ABC
USER
FEED
Note: "AB" represents package marking code.
"C" represents date code.
DIRECTION
COVER TAPE
For Outline SOT-143
For Outline SOT-363
TOP VIEW
4 mm
END VIEW
TOP VIEW
4 mm
END VIEW
8 mm
8 mm
A B C
A B C
A B C
A B C
ABC
ABC
ABC
ABC
Note: "AB" represents package marking code.
"C" represents date code.
Note: "AB" represents package marking code.
"C" represents date code.
16
Tape Dimensions and Product Orientation
For Outline SOT-23
P
P
D
2
E
F
P
0
W
D
1
t1
Ko
13.5° MAX
8° MAX
9° MAX
B
A
0
0
DESCRIPTION
SYMBOL
SIZE (mm)
SIZE (INCHES)
CAVITY
LENGTH
WIDTH
DEPTH
PITCH
A
B
K
P
3.15 0.10
2.77 0.10
1.22 0.10
4.00 0.10
1.00 + 0.05
0.124 0.004
0.109 0.004
0.048 0.004
0.157 0.004
0.039 0.002
0
0
0
BOTTOM HOLE DIAMETER
D
1
PERFORATION
CARRIER TAPE
DIAMETER
PITCH
POSITION
D
1.50 + 0.10
4.00 0.10
1.75 0.10
0.059 + 0.004
0.157 0.004
0.069 0.004
P
E
0
WIDTH
W
8.00+0.30–0.10 0.315+0.012–0.004
THICKNESS
t1
0.229 0.013
0.009 0.0005
DISTANCE
BETWEEN
CAVITY TO PERFORATION
(WIDTH DIRECTION)
F
3.50 0.05
0.138 0.002
CENTERLINE
CAVITY TO PERFORATION
(LENGTH DIRECTION)
P
2.00 0.05
0.079 0.002
2
For Outline SOT-143
P
D
P2
P0
E
F
W
D1
t1
K
0
9° MAX
9° MAX
A0
B
0
DESCRIPTION
SYMBOL
SIZE (mm)
SIZE (INCHES)
CAVITY
LENGTH
WIDTH
DEPTH
PITCH
A
B
K
P
3.19 0.10
2.80 0.10
1.31 0.10
4.00 0.10
1.00 + 0.25
0.126 0.004
0.110 0.004
0.052 0.004
0.157 0.004
0.039 + 0.010
0
0
0
BOTTOM HOLE DIAMETER
D
1
PERFORATION
DIAMETER
PITCH
POSITION
D
1.50 + 0.10
4.00 0.10
1.75 0.10
0.059 + 0.004
0.157 0.004
0.069 0.004
P
E
0
CARRIER TAPE
DISTANCE
WIDTH
THICKNESS
W
t1
8.00+0.30–0.10 0.315+0.012–0.004
0.254 0.013
0.0100 0.0005
CAVITY TO PERFORATION
(WIDTH DIRECTION)
F
3.50 0.05
0.138 0.002
CAVITY TO PERFORATION
(LENGTH DIRECTION)
P
2.00 0.05
0.079 0.002
2
17
Tape Dimensions and Product Orientation
For Outlines SOT-323, -363
P
P
D
2
P
0
E
F
W
C
D
1
t
(CARRIER TAPE THICKNESS)
T (COVER TAPE THICKNESS)
t
1
K
An
An
0
A
B
0
0
DESCRIPTION
SYMBOL
SIZE (mm)
SIZE (INCHES)
CAVITY
LENGTH
WIDTH
DEPTH
PITCH
A
B
K
P
2.40 0.10
2.40 0.10
1.20 0.10
4.00 0.10
1.00 + 0.25
0.094 0.004
0.094 0.004
0.047 0.004
0.157 0.004
0.039 + 0.010
0
0
0
BOTTOM HOLE DIAMETER
D
1
PERFORATION
DIAMETER
PITCH
POSITION
D
1.55 0.05
4.00 0.10
1.75 0.10
0.061 0.002
0.157 0.004
0.069 0.004
P
E
0
CARRIER TAPE
COVER TAPE
DISTANCE
WIDTH
THICKNESS
W
8.00 0.30
0.254 0.02
0.315 0.012
0.0100 0.0008
t
1
WIDTH
TAPE THICKNESS
C
5.4 0.10
0.062 0.001
0.205 0.004
0.0025 0.00004
T
t
CAVITY TO PERFORATION
(WIDTH DIRECTION)
F
3.50 0.05
0.138 0.002
CAVITY TO PERFORATION
(LENGTH DIRECTION)
P
2.00 0.05
0.079 0.002
2
ANGLE
FOR SOT-323 (SC70-3 LEAD)
FOR SOT-363 (SC70-6 LEAD)
An
8°C MAX
10°C MAX
Part Number Ordering Information
Part Number
No. of Devices
Container
HSMS‑286x‑TR2G
HSMS‑286x‑TR1G
HSMS‑286x‑BLKG
10000
3000
100
13” Reel
7” Reel
antistatic bag
where x = 0, 2, 3, 4, 5, B, C, E, F, K, L, P or R for HSMS‑286x.
For product information and a complete list of distributors, please go to our web site: www.avagotech.com
Avago, Avago Technologies, and the A logo are trademarks of Avago Technologies in the United States and other countries.
Data subject to change. Copyright © 2005-2009 Avago Technologies. All rights reserved. Obsoletes 5989-4023EN
AV02-1388EN - August 26, 2009
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