elektronika electronics - Electronics Journal - Elektrotehnicki fakultet

16
R[ohm]
6
4
2
0
0 1 2 3 4 5 6
Frequency[GHz]
Fig.3 Frequency dependence of parasitic resistances
The intrinsic elements of the small signal equivalent
model have been extracted at several bias conditions. The behavior
of the tranconductance gm at 56 bias points is reported
in Fig. 5 for a 900µm gate width device.
Fig.4 Frequency dependence of parasitic capacitances
The consistency of the extracted elements values has been
evaluated as a function of either the bias conditions and the
device dimensions. Both extrinsic ed intrinsic elements depend
on the gate width. As an example, in Fig 6 the behavior
of the transconductance is reported and clear scaling effects
can be seen.
gm [S]
C[pf]
0.12
0.08
0.04
0
0 1 2 3 4 5 6
VDS [V]
Frequency[GHz]
ELECTRONICS, VOL. 8, NO.1, MAY 2004.
VGS [V]
CPG
CPD
Rg
Rs
Rd
Fig.5 Bias conditions dependence of the transconductance g m
gm[S]
0.6
0.4
0.2
0
0 2 4 6
VDS
W=300
W=600
W=900
VGS=0V
Fig.6 Behavior of g m vs. V ds for devices of scaled gate widths
We report in Figs. 7-10 the comparison between the
measured and simulated [S] parameters sets, as outputs of the
AWR software, for a 900 µm device. This test thus gives a
demonstration of the fitting performance of the extracted
model.
0
0 .2
-0.2
0.4
0.2
-0.4
0.6
-0.6
0.4
0.8
0.6
-0.8
0.8
S11
1.0
1.0
-1 .0
2.0
3.0
-2.0
2.0
4.0
5.0
-3.0
Swp Max
6GHz
3.0
10 .0
4.0
-4 .0
5.0
10 .0
-10.0
-5.0
Swp Min
0.3475GHz
Fig. 7 S 11 parameter measured and modeled
Ma g Ma x
25
16 5
-180
150
-16 5
5
Per Div
-15 0
13 5
-135
120
-120
105
-105
S21
90
-90
75
-75
60
-60
45
-45
Swp Ma x
6 GHz
30
-30
1 5
-1 5
0
Swp Min
0.3475 GHz
Fig. 8 S 21 parameter measured and modeled