hsmp-3895 Avago Technologies, hsmp-3895 Datasheet - Page 7

• Manufacturer Part Number: hsmp-3895
• Description: Surface Mount Rf Pin Switch Diodes
• Manufacturer: Avago Technologies

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 ap-
plications, both lead 1 and lead 2 should be connected
together, as shown in Figure 17.
Figure 16. Internal Connections.
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 interrupted 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 cre-
ated by the via holes, and is a good estimate for 0.032"
thick material.
Figure 18. Circuit Layout.
Figure 18. Circuit Layout.
Figure 19. Equivalent Circuit.
Figure 19. Equivalent Circuit.
50 OHM MICROSTRIP LINES
7
Figure 17. Circuit Layout.
1.5 nH
1
HSMP-489x
PAD CONNECTED TO
GROUND BY TWO
3
VIA HOLES
0.3 nH
0.3 nH
2
0.3 pF
1.5 nH
R
C
R
Equivalent Circuit Model
HSMP-389x Chip*
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, car-
rier lifetime.
I = Forward Bias Current in mA
* See AN1124 for package mode
T
T
j
=
0.5 Ω
= 0.5 + R
= C
R
Figure 20. Circuit Layout.
Figure 21. Equivalent Circuit.
s
20
P
I
0.9
+ C
Ω
* Measured at -20 V
j
j
0.12 pF*
R
C
j
0.75 nH
j
0.3 pF
Co-Planar Waveguide
Groundplane
Center Conductor
Groundplane