HSMS-286C-TR1 Avago Technologies US Inc., HSMS-286C-TR1 Datasheet - Page 7

• 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

high value of current (such as
5 mA). This slope is converted
into a resistance R
For n-type diodes with relatively
low values of saturation current,
C
total capacitance (see AN1124).
R
calculated using the equation
given above.
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.
external DC bias sets the video
impedance of such circuits, they
display classic square law
response over a wide range of
input power levels
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
[1]
[2]
[3]
[4]
[5]
j
j
, the junction resistance, is
Agilent Application Note 923, Schottky Barrier Diode Video Detectors.
Agilent Application Note 986, Square Law and Linear Detection.
Agilent Application Note 956-5, Dynamic Range Extension of Schottky Detectors.
Agilent Application Note 956-4, Schottky Diode Voltage Doubler.
Agilent Application Note 963, Impedance Matching Techniques for Mixers and Detectors.
is obtained by measuring the
R
[1]
S
Moreover, since
= R
d
– ––––––
[2,3]
d
.
0.026
. These
I
f
[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 equivalent circuit
disappear at all reasonable video
frequencies. In general, the lower
the diode’s video impedance, the
better the design.
Figure 9. Basic Detector Circuits.
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.
RF
RF
IN
IN
NETWORK
NETWORK
Z-MATCH
Z-MATCH
DC BIAS
DC BIAS
L
1
VIDEO
OUT
L
1
VIDEO
OUT
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.
Design work begins with the RF
impedance of the HSMS-286x
series when bias current is set to
3 µA. See Figure 10.
Figure 10. RF Impedance of the
Diode.
0.2
7
0.6
6
R
V
1
= R
j
+ R
2
5
S
5
4
[5]
3
2
1 GHz