HSMS-286C-TR1 Avago Technologies US Inc., HSMS-286C-TR1 Datasheet - Page 8

• Manufacturer Part Number: HSMS-286C-TR1
• Description: DETECTOR DIODE,SOT-323
• Manufacturer: Avago Technologies US Inc.

Specifications of HSMS-286C-TR1

• Rohs Compliant: NO
• Diode Type: Schottky - 1 Pair Series Connection
• Voltage - Peak Reverse (max): 4V
• Capacitance @ Vr, F: 0.25pF @ 0V, 1MHz
• Package / Case: SC-70-3, SOT-323-3
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Max: -
• Power Dissipation (max): -
• Resistance @ If, F: -
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

915 MHz Detector Circuit
Figure 11 illustrates a simple
impedance matching network for
a 915 MHz detector.
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
simultaneously 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.
INPUT
RF
FREQUENCY (GHz): 0.9-0.93
65nH
TRANSMISSION LINE
DIMENSIONS ARE FOR
MICROSTRIP ON
0.032" THICK FR-4.
WIDTH = 0.015"
LENGTH = 0.600"
WIDTH = 0.050"
LENGTH = 0.065"
100 pF
VIDEO
OUT
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 applications.
The HSMS-282x family is a better
choice for 915 MHz applications—
the foregoing discussion of a
design using the HSMS-286B is
offered only to illustrate a design
approach for technique.
INPUT
Figure 14. 2.45 GHz Matching
Network.
RF
-10
-15
-20
-5
0
0.9
TRANSMISSION LINE
DIMENSIONS ARE FOR
MICROSTRIP ON
0.032" THICK FR-4.
WIDTH = 0.078"
LENGTH = 0.165"
WIDTH = 0.017"
LENGTH = 0.436"
FREQUENCY (GHz)
0.915
100 pF
VIDEO
OUT
0.93
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 Agilent.
Figure 16. Test Detector.
0.030" PLATED THROUGH HOLE,
RF IN
0.094" THROUGH, 4 PLACES
8
CHIP CAPACITOR, 20 TO 100 pF
3 PLACES
HSMS-2860
FINISHED
BOARD
SIZE IS
1.00" X 1.00".
MATERIAL IS
1/32" FR-4
EPOXY/
FIBERGLASS,
1 OZ. COPPER
BOTH SIDES.
VIDEO OUT