HMPP-389X Datasheet, PDF (7/11 Pages) Agilent(Hewlett-Packard) – MiniPak Surface Mount RF PIN Switch Diodes

0
-0.2
-0.4
-0.6
-0.8
-1.0
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2
3
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6
FREQUENCY (GHz)
Figure 16. Insertion loss of reference line.
To evaluate the HMPP-389T as
shunt switch, it was mounted on
the test line and then the appropri-
ate biasing voltage was applied. In
our prototype, the worst case
return loss was 10 dB at 5 GHz
(Figure 17). The return loss varied
very little when the bias was
changed from zero to -20V.
-5
-15
-25
-35
-45
-55
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FREQUENCY (GHz)
Figure 17. Return loss of HMPP-389T mounted
on test line at 0V and -20V bias.
Normalization was used to remove
the pcb’s and connectors’ losses
from the measurement of the
shunt switch’s loss. The active
trace was divided by the memo-
rized trace (Data/Memory) to
produce the normalized data. At
zero bias, the insertion loss was
under 0.6 dB up to 6 GHz (Figure
18). Applying a reverse bias to the
PIN diode has the effect of
reducing its parasitic capacitance.
With a reverse bias of -20V, the
insertion loss improved to better
than 0.5 dB (Figure 19).
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-1.0
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FREQUENCY (GHz)
Figure 18. Insertion loss of HMPP-389T at 0V.
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FREQUENCY (GHz)
Figure 19. Insertion loss of HMPP-389T at -20V.
The PIN diode’s resistance is a
function of the bias current. So, at
higher forward current, the
isolation improved. The combina-
tion of the HMPP-389T and the
SK063A demoboard exhibited
more than 17 dB of isolation from
1 to 6 GHz at If ≥ 1mA (Figure 20).
-10
0.15 mA
-14 ^{0.25 mA}
0.5 mA
-18 1 mA
-22 ^{1.5 mA}
-26
20 mA
-30
1
2
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5
6
FREQUENCY (GHz)
Figure 20. Isolation at different frequencies
with forward current as a parameter.
The combination of the
HMPP-389T and the demo-board
allows a high performance shunt
switch to be constructed swiftly
and economically. The extremely
low parasitic inductance of the
package allows the switch to
operate over a very wide fre-
quency range.
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