HSMP-489x Agilent Technologies, HSMP-489x Datasheet - Page 7

• Manufacturer Part Number: HSMP-489x
• Description: (HSMP-389x / HSMP-489x) Pin Switch Diode
• Manufacturer: Agilent Technologies

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Typical Applications for
HSMP-489x Low
Inductance Series
Microstrip Series Connection
for HSMP-489x Series
In order to take full advantage of
the low inductance of the
HSMP-489x series when using
them in series applications, both
lead 1 and lead 2 should be
connected together, as shown in
Figure 17.
Figure 16. Internal Connections.
Figure 17. Circuit Layout.
Microstrip Shunt Connections
for HSMP-489x Series
In Figure 18, the center conductor
of the microstrip line is inter-
rupted and leads 1 and 2 of the
HSMP-489x diode are placed
across the resulting gap. This
forces the 1.5 nH lead inductance
of leads 1 and 2 to appear as part
of a low pass filter, reducing the
shunt parasitic inductance and
increasing the maximum available
attenuation. The 0.3 nH of shunt
inductance external to the diode
is created by the via holes, and is
a good estimate for 0.032" thick
material.
1
HSMP-489x
3
2
Figure 18. Circuit Layout.
Figure 19. Equivalent Circuit.
Equivalent Circuit Model
HSMP-389x Chip*
R
C
R
I = Forward Bias Current in mA
* See AN1124 for package models
T
T
j
=
0.5
= 0.5 + R
= C
R
s
20
I
50 OHM MICROSTRIP LINES
P
0.9
1.5 nH
+ C
j
* Measured at -20 V
j
PAD CONNECTED TO
GROUND BY TWO
0.12 pF*
R
VIA HOLES
C
j
0.3 nH
0.3 nH
j
0.3 pF
1.5 nH
Co-Planar Waveguide Shunt
Connection for HSMP-489x
Series
Co-Planar waveguide, with
ground on the top side of the
printed circuit board, is shown in
Figure 20. Since it eliminates the
need for via holes to ground, it
offers lower shunt parasitic
inductance and higher maximum
attenuation when compared to a
microstrip circuit.
Figure 20. Circuit Layout.
Figure 21. Equivalent Circuit.
A SPICE model is not available
for PIN diodes as SPICE does not
provide for a key PIN diode
characteristic, carrier lifetime.
7
0.75 nH
0.3 pF
Co-Planar Waveguide
Groundplane
Center Conductor
Groundplane