HSMS-286x Series
Surface Mount Microwave Schottky Detector Diodes
Data Sheet
SOT-23/SOT-143 Package Lead Code Identification
(top view)
Description
Avago’s HSMS‑286x family of DC biased detector diodes
have been designed and optim ized for use from 915 MHz
to 5.8 GHz. They are ideal for RF/ID and RF Tag applications
as well as large signal detection, modulation, RF to DC
conversion or voltage doubling.
Available in various package con figurations, 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.
Pin Connections and Package Marking
SOT-323 Package Lead Code Identification (top view)
Notes:
1. Package marking provides orientation and identification.
2. The first two characters are the package marking code.
The third character is the date code.
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
• 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
• HSMS‑286K Grounded Center Leads Provide up to
10 dB Higher Isolation
• Matched Diodes for Consistent Performance
• Better Thermal Conductivity for Higher Power
Dissipation
• Lead‑free
* For more information see the Surface Mount Schottky Reliability
Data Sheet.
PLx
1
2
3
6
5
4
SOT-363 Package Lead Code Identification (top view)
SERIES
C
SINGLE
B
1 2
3
1 2
3
COMMON
CATHODE
F
COMMON
ANODE
E
1 2
3
1 2
3
BRIDGE
QUAD
P
UNCONNECTED
TRIO
L
RING
QUAD
R
1 2 3
6 5 4
1 2 3
6 5 4
1 2 3
6 5 4
HIGH ISOLATION
UNCONNECTED PAIR
K
1 2 3
6 5 4
COMMON
CATHODE
#4
UNCONNECTED
PAIR
#5
COMMON
ANODE
#3
SERIES
#2
SINGLE
#0
1 2
3
1 2
3 4
1 2
3
1 2
3
1 2
3
2
SOT-23/SOT-143 DC Electrical Specifications, TC = +25°C, Single Diode
Part Package Typical
Number Marking Lead Forward Voltage Capacitance
HSMS- Code Code Configuration VF (mV) CT (pF)
2860 T0 0 Single 250 Min. 350 Max. 0.30
2862 T2 2 Series Pair[1,2]
2863 T3 3 Common Anode[1,2]
2864 T4 4 Common Cathode[1,2]
2865 T5 5 Unconnected Pair [1,2]
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 Package Typical
Number Marking Lead Forward Voltage Capacitance
HSMS- Code Code Configuration VF (mV) CT (pF)
286B T0 B Single 250 Min. 350 Max. 0.25
286C T2 C Series Pair[1,2]
286E T3 E Common Anode[1,2]
286F T4 F Common Cathode[1,2]
286K TK K High Isolation
Unconnected Pair
286L TL L Unconnected Trio
286P TP P Bridge Quad
286R ZZ 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.
3
RF Electrical Specifications, TC = +25°C, Single Diode
Part Typical Tangential Sensitivity Typical Voltage Sensitivity g Typical Video
Number TSS (dBm) @ f = (mV/µW) @ f = Resistance
HSMS- 915 MHz 2.45 GHz 5.8 GHz 915 MHz 2.45 GHz 5.8 GHz RV (KΩ)
2860 – 57 –56 –55 50 35 25 5.0
2862
2863
2864
2865
286B
286C
286E
286F
286K
286L
286P
286R
Test Video Bandwidth = 2 MHz Power in = –40 dBm Ib = 5 µA
Conditions Ib = 5 µA RL = 100 KΩ, Ib = 5 µA
Absolute Maximum Ratings, TC = +25°C, Single Diode
Symbol Parameter Unit Absolute Maximum[1]
SOT-23/143 SOT-323/363
PIV Peak Inverse Voltage V 4.0 4.0
TJ Junction Temperature °C 150 150
TSTG Storage Temperature °C ‑65 to 150 ‑65 to 150
TOP Operating Temperature °C ‑65 to 150 ‑65 to 150
θjc Thermal Resistance[2] °C/W 500 150
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.
ESD Machine Model (Class A)
ESD Human Body Model (Class 0)
Refer to Avago Application Note A004R:
Electro-
static Discharge Damage and Control.
Attention:
Observe precautions for
handling electrostatic
sensitive devices.
4
Equivalent Linear Circuit Model, Diode chip SPICE Parameters
Parameter Units Value
BV V 7.0
CJ0 pF 0.18
EG eV 0.69
IBV A 1 E ‑ 5
IS A 5 E ‑ 8
N 1.08
RS Ω 6.0
PB (VJ) V 0.65
PT (XTI) 2
M 0.5
Cj
Rj
RS
Rj = 8.33 X 10-5 nT
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.
RS = series resistance (see Table of SPICE parameters)
Cj = junction capacitance (see Table of SPICE parameters)
5
Typical Parameters, Single Diode
1
10
100
1
10
FORWARD VOLTAGE DIFFERENCE(mV)
VOLTAGE OUT (mV)
POWER IN (dBm)
0.05 0.15 0.200.10 0.25
FORWARD VOLTAGE (V)
.01
.1
1
10
100
0.1 0.2 0.3 0.4 0. 70.6 0.8 0.90.5 1.0
FORWARD CURRENT (mA)
FORWARD VOLTAGE (V)
1
10
100
1000
10,000
–40 –30 –10 0–20 10 5
35
30
40
10
15
20
25
.1 1 1 0 100
OUTPUT VOLTAGE (mV)
BIAS CURRENT (µA)
TA = –55°C
TA = +25°C
TA = +85°C
IF (left scale)
VF (right scale)
Frequency = 2.45 GHz
Fixed-tuned FR4 circuit
RL = 100 KΩ
20 µA
5 µA
10 µA
Input Power =
–30 dBm @ 2.45 GHz
Data taken in fixed-tuned
FR4 circuit
RL = 100 KΩ
VOLTAGE OUT (mV)
-50
0.1
POWER IN (dBm)
-30 -2 0
10000
10
1
-40 0
100
-1 0
1000
RL = 100 KΩ
5.8 GHz
DIODES TESTED IN FIXED-TUNED
FR4 MICROSTRIP CIRCUITS.
915 MHz
2.45 GHz
VOLTAGE OUT (mV)
-50
0.3
POWER IN (dBm)
-30
10
1
-40
30
RL = 100 KΩ
2.45 GHz
915 MHz
5.8 GHz
DIODES TESTED IN FIXED-TUNED
FR4 MICROSTRIP CIRCUITS.
FORWARD CURRENT (mA)
FORWARD CURRENT (mA)
6
Appli cations Information
Introduction
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.
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
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.
The Height of the Schottky Barrier
The current‑voltage character istic of a Schottky barrier
diode at room temperature is described by the following
equation:
HSMS-285A/6A fig 9
R
S
R
j
C
j
METAL
SCHOTTKY JUNCTION
PASSIVATION PASSIVATION
N-TYPE OR P-TYPE EPI LAYER
N-TYPE OR P-TYPE SILICON SUBSTRATE
CROSS-SECTION OF SCHOTTKY
BARRIER DIODE CHIP
EQUIVALENT
CIRCUIT
Figure 7. Schottky Diode Chip.
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 capaci tance
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
S
R
V
C
j
Figure 8. Equivalent Circuit of a Schottky Diode Chip.
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.
8.33 X 10 -5 n T
Rj = = R V - R s
IS + I b
0.026
= at 25°C
IS + I b
V - IR S
I = I S (exp ( ) - 1)
0.026
8.33 X 10 -5 n T
Rj = = R V - R s
IS + I b
0.026
= at 25°C
IS + I b
V - IR S
I = I S (exp ( ) - 1)
0.026
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
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.
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
deter mined by the saturation current, IS, and is related to
the barrier height of the diode.
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 applica tions) 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.
Measuring Diode Linear Parameters
The measurement of the many elements which make
up the equivalent circuit for a pack aged 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).
RV = R j + R S
0.026
RS = R d - If
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.
7
The characterization of the surface mount package is
too complex to describe here — linear equivalent circuits
can be found in AN1124.
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.
Output voltage can be virtually doubled and input
impedance (normally very high) can be halved through
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.
The situation is somewhat more complicated in the
design of the RF impedance matching net work, which
includes the pack age 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 equiv alent circuit, the parasitics
are constants and the video resistance is a function of
the current flowing through the diode.
[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.
HSMS-285A/6A fig 12
VIDEO
OUT
RF
IN
Z-MATCH
NETWORK
L
1
DC BIAS
VIDEO
OUT
Z-MATCH
NETWORK
L
1
DC BIAS
RF
IN
Figure 9. Basic Detector Circuits.
Figure 10. RF Impedance of the Diode.
RV = R j + R S
0.026
RS = R d - If
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].
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.
When maximum sensitivity is required over a narrow
band of frequencies, a reactive matching network is
optimum. Such net works 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.
8
915 MHz Detector Circuit
Figure 11 illustrates a simple impedance matching network
for a 915 MHz detector.
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.
HSMS-285A/6A fig 14
65nH
100 pF
VIDEO
OUT
RF
INPUT
WIDTH = 0.050"
LENGTH = 0.065"
WIDTH = 0.015"
LENGTH = 0.600"
TRANSMISSION LINE
DIMENSIONS ARE FOR
MICROSTRIP ON
0.032" THICK FR-4.
HSMS-285A/6A fig 15
FREQUENCY (GHz): 0.9-0.93
HSMS-285A/6A fig 16
RETURN LOSS (dB)
0.9
-20
FREQUENCY (GHz)
0.915
0
-10
-15
0.93
-5
100 pF
VIDEO
OUT
RF
INPUT
WIDTH = 0.017"
LENGTH = 0.436"
WIDTH = 0.078"
LENGTH = 0.165"
TRANSMISSION LINE
DIMENSIONS ARE FOR
MICROSTRIP ON
0.032" THICK FR-4.
0.030" PLATED THROUGH HOLE,
3 PLACES
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.
HSMS-2860 fig 15
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 Figure 12.
Figure 12. Input Impedance.
The input match, expressed in terms of return loss, is
given in Figure 13.
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.
Figure 14. 2.45 GHz Matching Network.
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.
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.
CHIP CAPACITOR, 20 TO 100 pF
HSMS-2860
HSMS-285X fig 20 was 17
VIDEO OUTRF IN
Figure 16. Test Detector.
9
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.
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.
HSMS-0005 fig 21 was 18
FREQUENCY (GHz): 2.3-2.6
HSMS-285X fig 22 was 19
RETURN LOSS (dB)
2.3
-20
FREQUENCY (GHz)
2.45
0
-10
-15
2.6
-5
HSMS-0005 fig 23 was 20
FREQUENCY (GHz): 2.3-2.6
2.45 GHz
HSMS-285X fig 24 was 21
RETURN LOSS (dB)
2.3
-20
FREQUENCY (GHz)
2.45
0
-10
-15
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.
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.
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 mid band frequency of his circuit
if there is any small deviation in circuit board or diode
character istics 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.
5.8 GHz Detector Circuit
A possible design for a 5.8 GHz detector is given in Figure
21.
20 pF
VIDEO
OUT
RF
INPUT
WIDTH = 0.016"
LENGTH = 0.037"
WIDTH = 0.045"
LENGTH = 0.073"
TRANSMISSION LINE
DIMENSIONS ARE FOR
MICROSTRIP ON
0.032" THICK FR-4.
Figure 21. 5.8 GHz Matching Network for the HSMS-286x Series at 3 µA Bias.
10
As was the case at 2.45 GHz, the circuit is entirely dis‑
tributed element, both low cost and compact. Input
impedance for this network is given in Figure 22.
Such a circuit offers several advantages. First the voltage
outputs of two diodes are added in series, increasing
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 inter rogator, the Schottky circuit will
produce power sufficient to operate an I.C. or to charge
up a capacitor for a burst transmis sion from an oscilla‑
tor. Where such virtual batteries are employed, the bulk,
cost, and limited lifetime of a battery are eliminated.
Temperature Compensation
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
8.33 x 10‑5 nT
RV =
IS + Ib
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.
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.
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.
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.
HSMS-0005 fig 26 was 23
FREQUENCY (GHz): 5.6-6.0
HSMS-285X fig 27 was 24
RETURN LOSS (dB)
5.6
-20
FREQUENCY (GHz)
5.8
0
-10
-15
6.0
-5
5.9
5.7
HSMS-285X fig 11 was 7
VIDEO OUT
Z-MATCH
NETWORK
RF IN
Figure 22. Input Impedance.
Input return loss, shown in Figure 23, exhibits wideband
match.
Figure 23. Input Return Loss.
Voltage Doublers
To this point, we have restricted our discus sion 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.
Figure 24. Voltage Doubler Circuit.
11
Figure 25. Output Voltage vs. Temperature and Bias Current
in the 915 MHz Voltage Doubler using the HSMS-286C.
in a single package, such as the SOT‑143 HSMS‑2865 as
shown in Figure 29.
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.
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.
-55 -35 -15 5 8545 65
OUTPUT VOLTAGE (mV)
TEMPERATURE (°C)
25
40
80
60
120
100
INPUT POWER = –30 dBm
3.0 µA
1.0 µA
10 µA
0.5 µA
OUTPUT VOLTAGE (mV)
TEMPERATURE (
°
C)
5
15
35
25
INPUT POWER = –30 dBm
3.0 µA
10 µA
1.0 µA
0.5 µA
-55 -35 -15 5 8545 6525
matching
network
differential
amplifier
bias
to differential
amplifier
V
s
detector
diode
reference diode
PA
HSMS-2865
Figure 26. Output Voltage vs. Temperature and Bias Current
in the 5.80 GHz Voltage Detector using the HSMS-286B Schottky.
Six Lead Circuits
The differential detector is often used to provide temper‑
ature compensation for a Schottky detector, as shown in
Figures 27 and 28.
Figure 27. Differential Detector.
Figure 28. Conventional Differential Detector.
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
HSMS-2865
SOT-143
HSMS-286K
SOT-363
3 4 6 5 4
11 2 2 3
to differential
amplifier
V
s
detector
diode
reference diode
PA
HSMS-286K
-35 -25 -15 -5 155
37 dB
47 dB
OUTPUT VOLTAGE (mV)
INPUT POWER (dBm)
0.5
1000
100
10
1
5000
Frequency = 900 MHz
HSMS-2825
ref. diode
RF diode
Vout
Square law
response
HSMS-282K
ref. diode
Figure 29. Comparing Two Diodes.
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.
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.
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.
Figure 31. Comparing HSMS-282K with HSMS-2825.
12
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.
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.
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,
matching
network
bias
differential
amplifier
Figure 32. Differential Voltage Doubler, HSMS-286P.
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.
Other configurations of six lead Schottky products can
be used to solve circuit design problems while saving
space and cost.
Thermal Considerations
The obvious advantage of the SOT‑363 over the SOT‑
143 is combination of smaller size and two extra leads.
However, the copper leadframe in the SOT‑323 and SOT‑
363 has a thermal conductivity four times higher than
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:
11600 (V f- I f R s)
nT
If = I S e - 1
Equation (3).
2 1 1
n - 4060 (T- 298)
Is = I 0 ( T ) e
298
Equation (4).
Tj = (V fIf + P RF )θjc + T aEquation (1).
θjc = θpkg + θchip Equation (2).
11600 (V f- I f R s)
nT
If = I S e - 1
Equation (3).
2 1 1
n - 4060 (T- 298)
Is = I 0 ( T ) e
298
Equation (4).
Tj = (V fIf + P RF )θjc + T aEquation (1).
θjc = θpkg + θchip Equation (2).
11600 (V f- I f R s)
nT
If = I S e - 1
Equation (3).
2 1 1
n - 4060 (T- 298)
Is = I 0 ( T ) e
298
Equation (4).
Tj = (V fIf + P RF )θjc + T aEquation (1).
θjc = θpkg + θchip Equation (2).
11600 (V f- I f R s)
nT
If = I S e - 1
Equation (3).
2 1 1
n - 4060 (T- 298)
Is = I 0 ( T ) e
298
Equation (4).
Tj = (V fIf + P RF )θjc + T aEquation (1).
θjc = θpkg + θchip Equation (2).
where
Tj = junction temperature
Ta = diode case temperature
θjc = thermal resistance
VfIf = DC power dissipated
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.
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:
where
n = ideality factor
T = temperature in °K
Rs = diode series resistance
and IS (diode saturation current) is given by
Equations (1) and (3) are solved simultaneously to obtain
the value of junction temperature for given values of
diode case temperature, DC power dissipation and RF
power dissipation.
13
Diode Burnout
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.
Avago offers a com plete 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.
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.
0.026
0.039
0.079
0.022
Dimensions in inches
0.026
0.075
0.016
0.035
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
assembly equipment without adding parasitics that could
impair the performance.
Assembly Instructions
SOT-323 PCB Footprint
A recommended PCB pad layout for the miniature SOT‑
323 (SC‑70) package is shown in Figure 33 (dimensions
are in inches).
14
Figure 35. Surface Mount Assembly Profile.
SMT Assembly
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.
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.
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
25
Time
Temperature
Tp
T
L
tp
t
L
t 25° C to Peak
Ramp-up
ts
Ts
min
Ramp-down
Preheat
Critical Zone
T
L
to Tp
Ts
max
Lead-Free Reflow Profile Recommendation (IPC/JEDEC J-STD-020C)
Reflow Parameter Lead-Free Assembly
Average ramp‑up rate (Liquidus Temperature (TS(max) to Peak) 3°C/ second max
Preheat Temperature Min (TS(min)) 150°C
Temperature Max (TS(max)) 200°C
Time (min to max) (tS) 60‑180 seconds
Ts(max) to TL Ramp‑up Rate 3°C/second max
Time maintained above: Temperature (TL) 217°C
Time (tL) 60‑150 seconds
Peak Temperature (TP) 260 +0/‑5°C
Time within 5 °C of actual Peak temperature (tP) 20‑40 seconds
Ramp‑down Rate 6°C/second max
Time 25 °C to Peak Temperature 8 minutes max
Note 1: All temperatures refer to topside of the package, measured on the package body surface
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.
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.
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.
15
Package Dimensions
Outline 23 (SOT-23)
Outline 143 (SOT-143) Outline SOT-363 (SC-70 6 Lead)
Outline SOT-323 (SC-70 3 Lead)
eB
e2
B1
e1
E1
C
EXXX
L
D
A
A1
Notes:
XXX-package marking
Drawings are not to scale
DIMENSIONS (mm)
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
SYMBOL
A
A1
B
B1
C
D
E1
e
e1
e2
E
L
e
B
e2
e1
E1
C
EXXX
L
D
A
A1
Notes:
XXX-package marking
Drawings are not to scale
DIMENSIONS (mm)
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
SYMBOL
A
A1
B
C
D
E1
e
e1
e2
E
L
e
B
e1
E1
C
EXXX
L
D
A
A1
Notes:
XXX-package marking
Drawings are not to scale
DIMENSIONS (mm)
MIN.
0.80
0.00
0.15
0.08
1.80
1.10
1.80
0.26
MAX.
1.00
0.10
0.40
0.25
2.25
1.40
2.40
0.46
SYMBOL
A
A1
B
C
D
E1
e
e1
E
L
1.30 typical
0.65 typical
E
HE
D
e
A1
b
A
A2
DIMENSIONS (mm)
MIN.
1.15
1.80
1.80
0.80
0.80
0.00
0.15
0.08
0.10
MAX.
1.35
2.25
2.40
1.10
1.00
0.10
0.30
0.25
0.46
SYMBOL
E
D
HE
A
A2
A1
e
b
c
L
0.650 BCS
L
c
16
Device Orientation
USER
FEED
DIRECTION
COVER TAPE
CARRIER
TAPE
REEL
For Outline SOT-143
For Outlines SOT-23, -323
Note: "AB" represents package marking code.
"C" represents date code.
END VIE
W
8 mm
4 mm
TOP VIEW
ABC ABC ABC ABC
END VIE
W
8 mm
4 mm
TOP VIEW
Note: "AB" represents package marking code.
"C" represents date code.
ABC ABC ABC ABC
For Outline SOT-363
Note: "AB" represents package marking code.
"C" re
p
resents date code.
END VIE
W
8 mm
4 mm
TOP VIEW
ABC ABC ABC ABC
17
Tape Dimensions and Product Orientation
For Outline SOT-23
9° MAX
A0
P
P0
D
P2
E
F
W
D1
Ko 8° MAX
B0
13.5° MAX
t1
DESCRIPTION SYMBOL SIZE (mm) SIZE (INCHES)
LENGTH
WIDTH
DEPTH
PITCH
BOTTOM HOLE DIAMETER
A0
B0
K0
P
D1
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
CAVITY
DIAMETER
PITCH
POSITION
D
P0
E
1.50 + 0.10
4.00 ± 0.10
1.75 ± 0.10
0.059 + 0.004
0.157 ± 0.004
0.069 ± 0.004
PERFORATION
WIDTH
THICKNESS
W
t1
8.00 + 0.30 – 0.10
0.229 ± 0.013
0.315 + 0.012 – 0.004
0.009 ± 0.0005
CARRIER TAPE
CAVITY TO PERFORATION
(WIDTH DIRECTION)
CAVITY TO PERFORATION
(LENGTH DIRECTION)
F
P2
3.50 ± 0.05
2.00 ± 0.05
0.138 ± 0.002
0.079 ± 0.002
DISTANCE
BETWEEN
CENTERLINE
For Outline SOT-143
W
F
E
P
2
P
0
D
P
D
1
DESCRIPTION SYMBOL SIZE (mm) SIZE (INCHES)
LENGTH
WIDTH
DEPTH
PITCH
BOTTOM HOLE DIAMETER
A
0
B
0
K
0
P
D
1
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
CAVITY
DIAMETER
PITCH
POSITION
D
P
0
E
1.50 + 0.10
4.00 ± 0.10
1.75 ± 0.10
0.059 + 0.004
0.157 ± 0.004
0.069 ± 0.004
PERFORATION
WIDTH
THICKNESS
W
t1
8.00 + 0.30 – 0.10
0.254 ± 0.013
0.315+ 0.012 – 0.004
0.0100 ± 0.0005
CARRIER TAPE
CAVITY TO PERFORATION
(WIDTH DIRECTION)
CAVITY TO PERFORATION
(LENGTH DIRECTION)
F
P
2
3.50 ± 0.05
2.00 ± 0.05
0.138 ± 0.002
0.079 ± 0.002
DISTANCE
A
0
9° MAX 9° MAX
t
1
B
0
K
0
Tape Dimensions and Product Orientation
For Outlines SOT-323, -363
P
P
0
P
2
F
W
C
D
1
D
E
A
0
An
t
1
(CARRIER TAPE THICKNESS) T
t
(COVER TAPE THICKNESS)
An
B
0
K
0
DESCRIPTION SYMBOL SIZE (mm) SIZE (INCHES)
LENGTH
WIDTH
DEPTH
PITCH
BOTTOM HOLE DIAMETER
A
0
B
0
K
0
P
D
1
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
CAVITY
DIAMETER
PITCH
POSITION
D
P
0
E
1.55 ± 0.05
4.00 ± 0.10
1.75 ± 0.10
0.061 ± 0.002
0.157 ± 0.004
0.069 ± 0.004
PERFORATION
WIDTH
THICKNESS
W
t
1
8.00 ± 0.30
0.254 ± 0.02
0.315 ± 0.012
0.0100 ± 0.0008
CARRIER TAPE
CAVITY TO PERFORATION
(WIDTH DIRECTION)
CAVITY TO PERFORATION
(LENGTH DIRECTION)
F
P
2
3.50 ± 0.05
2.00 ± 0.05
0.138 ± 0.002
0.079 ± 0.002
DISTANCE
FOR SOT-323 (SC70-3 LEAD) An 8°C MAX
FOR SOT-363 (SC70-6 LEAD) 10°C MAX
ANGLE
WIDTH
TAPE THICKNESS
C
T
t
5.4 ± 0.10
0.062 ± 0.001
0.205 ± 0.004
0.0025 ± 0.00004
COVER TAPE
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
Part Number Ordering Information
Part Number No. of Devices Container
HSMS‑286x‑TR2G 10000 13” Reel
HSMS‑286x‑TR1G 3000 7” Reel
HSMS‑286x‑BLKG 100 antistatic bag
where x = 0, 2, 3, 4, 5, B, C, E, F, K, L, P or R for HSMS‑286x.