HSMS-285P-BLKG Avago Technologies US Inc., HSMS-285P-BLKG Datasheet - Page 7

• Manufacturer Part Number: HSMS-285P-BLKG
• Description: Diode RF Detector Schottky 2V 6-Pin SOT-363 Bulk
• Manufacturer: Avago Technologies US Inc.
• Type: Schottky Dioder

Specifications of HSMS-285P-BLKG

• Package: 6SOT-363
• Configuration: Quad Bridge
• Frequency Range: UHF
• Maximum Forward Voltage: 0.25@1mA V
• Maximum Reverse Voltage: 2 V
• Maximum Processing Temperature: 260 °C
• Maximum Diode Capacitance: 0.3(Typ) pF
• Typical Video Resistance: 8 KOhm
• Typical Voltage Sensitivity: 40@915MHz mV/uW
• Typical Tangential Sensitivity: -57@915MHz dB
• Diode Type: Schottky - 2 Pair Series Connection
• Voltage - Peak Reverse (max): 2V
• Capacitance @ Vr, F: 0.3pF @ 1V, 1MHz
• Package / Case: SC-70-6, SC-88, SOT-363
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Max: -
• Power Dissipation (max): -
• Resistance @ If, F: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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 networks can be realized in either
lumped or distributed elements, depending upon fre-
quency, size constraints and cost limitations, but certain
general design principals exist for all types.
work begins with the RF impedance of the HSMS-285x
series, which is given in Figure 9.
Figure 9. RF Impedance of the HSMS-285x Series at-40 dBm.
915 MHz Detector Circuit
Figure 10 illustrates a simple impedance matching
network for a 915 MHz detector.
INPUT
Figure 10. 915 MHz Matching Network for the HSMS-285x Series at Zero 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 11.
7
0.2
RF
0.6
HSMS-285A/6A fig 13
65nH
6
TRANSMISSION LINE
DIMENSIONS ARE FOR
MICROSTRIP ON
0.032" THICK FR-4.
WIDTH = 0.015"
LENGTH = 0.600"
HSMS-285A/6A fig 14
WIDTH = 0.050"
LENGTH = 0.065"
1
2
5
5
4
100 pF
3
2
1 GHz
VIDEO
OUT
[3]
Design
HSMS-285X fig 11 was 7
Figure 11. Input Impedance.
The input match, expressed in terms of return loss, is
given in Figure 12.
Figure 12. 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.
Voltage Doublers
To this point, we have restricted our discussion to single
diode detectors. A glance at Figure 8, however, will lead
to the suggestion that the two types of single diode de-
tectors be combined into a two diode voltage doubler
(known also as a full wave rectifier). Such a detector is
shown in Figure 13.
Figure 13. Voltage Doubler Circuit.
[2]
[3]
and Detectors.
RF IN
Avago Application Note 969, An Optimum Zero Bias Schottky Detector Diode.
Avago Application Note 963, Impedance Matching Techniques for Mixers
-10
-15
-20
FREQUENCY (GHz): 0.9-0.93
-5
0
0.9
HSMS-285A/6A fig 15
NETWORK
Z-MATCH
HSMS-285A/6A fig 16
FREQUENCY (GHz)
0.915
VIDEO OUT
0.93
[4]