5
Typical Applications for HSMP-481x Low Inductance Series (continued)
Co-Planar Waveguide
Shunt Connection for
HSMP-481x Series
Co-Planar waveguide, with
ground on the top side of the
printed circuit board, is shown
in Figure 10. 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.
Co-Planar Waveguide
Groundplane
Center Conductor
Groundplane
Figure 10. Circuit Layout.
R
j
0.3 pF
0.75 nH
Figure 11. Equivalent Circuit.
Equivalent Circuit Model
HSMS-381x Chip*
R
s
R
j
2.5
Ω
C
j
R
T
= 2.5 + R
j
0.18 pF*
C
T
= C
P
+ C
j
* Measured at -20 V
80
R
j
=
0.9
Ω
I
I = Forward Bias Current in mA
*See AN1124 for package models.
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