L
OW
N
OISE
, H
IGH
L
INEARITY
P
ACKAGED
PHEMT
FPD2250SOT89
•
TYPICAL I-V CHARACTERISTICS
DC IV Curves FPD2250SOT89
0.90
0.80
0.70
Drain-Source Current (A)
0.60
0.50
0.40
0.30
0.20
0.10
0.00
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Drain-Source Voltage (V)
VG=-1.50V
VG=-1.25V
VG=-1.00V
VG=-0.75V
VG=-0.50V
VG=-0.25V
VG=0V
Note: The recommended method for measuring I
DSS
, or any particular I
DS
, is to set the Drain-Source
voltage (V
DS
) at 1.3V. This measurement point avoids the onset of spurious self-oscillation which
would normally distort the current measurement (this effect has been filtered from the I-V curves
presented above). Setting the V
DS
> 1.3V will generally cause errors in the current measurements,
even in stabilized circuits.
Recommendation: Traditionally a device’s I
DSS
rating (I
DS
at V
GS
= 0V) was used as a predictor of
RF power, and for MESFETs there is a correlation between I
DSS
and P
1dB
(power at 1dB gain
compression). For pHEMTs it can be shown that there is
no
meaningful statistical correlation
between I
DSS
and P
1dB
; specifically a linear regression analysis shows r
2
< 0.7, and the regression
fails the F-statistic test. I
DSS
is sometimes useful as a guide to circuit tuning, since the S
22
does vary
with the quiescent operating point I
DS
.
Phone:
+1 408 850-5790
Fax:
+1 408 850-5766
http://www.filtronic.co.uk/semis
Revised:
01/05/05
Email:
sales@filcsi.com
FILTRONIC [ FILTRONIC COMPOUND SEMICONDUCTORS ]
