mga-83563-blk Avago Technologies, mga-83563-blk Datasheet - Page 14

• Manufacturer Part Number: mga-83563-blk
• Description: +22 Dbm Psat 3v Power Amplifier For 0.5? 6 Ghz Applications
• Manufacturer: Avago Technologies

The power-added efficiency
(PAE) in the saturated mode is
36% as calculated from:
Note the current increases
slightly from small signal condi-
tions to the 1 dB compression
point, then falls appreciably as
the amplifier goes into saturation.
(The 1-dB compressed output
power will be higher for amplifi-
ers that are tuned for linear
performance.)
P
Inductor L2
The output match of the com-
pleted 2.5 GHz amplifier was held
fixed while various values of L2
were substituted for the purposes
of (1) verifying the optimum
value for L2, and (2) determining
the sensitivity of P
the value of L2. These results are
plotted in Figure 31.
The data in Figure 31 indicates
there is some tradeoff between
tuning for maximum output
power and maximum efficiency.
The original choice of 1.5 nH for
the interstage inductor L2 ap-
pears well optimized.
The results of this tuning process
supplied the 2.5 GHz data point
referred to in the Appendix that
was used to create Plot B of
Figure 47.
Output Match Sensitivity
The sensitivity of P
the value of the shunt capacitor in
the output matching circuit was
investigated by varying the value
of C2 while noting P
current. The input power was
fixed at +4 dBm for this test.
sat
and PAE Sensitivity to
PAE =
PAE =
Σ
(P
out –
P
P
P
sat
sat
DC
RF
DC
sat
and PAE to
P
and PAE to
in
and device
)
The length of the series line
between the output of the
MGA-83563 and C2 is also part of
the matching circuit. This line was
not considered as a variable in the
sensitivity analysis since photo-
fabrication of micro-striplines on
circuit boards is highly repeatable.
P
are plotted in Figure 32.
Inspection of Figure 32 reveals
that a variation in C2 of ±10% is
acceptable for most applications.
sat
19.5
18.5
22.5
21.5
20.5
25
20
15
10
21
23
22
20
19
18
5
0
and PAE for each value of C2
0
Figure 31. 2.5 GHz P
Figure 32. 2.5 GHz P
0
0.5
0.5
1
sat
sat
and PAE vs. L2.
and PAE vs. C2.
1.5
P
sat
L2 (nH)
C2 (pF)
1
2
P
The most important observation
of this data is that the PAE
remains high for values of C2 that
are toward the left of the maxi-
mum P
C2), while the PAE begins to drop
off toward for higher values of
C2. This data points out the
importance of choosing a value
for C2 that is toward the lower
side of the maximum P
(lower C2) in order to maintain
high efficiency with production
tolerance components.
sat
PAE
14
2.5
sat
PAE
point (lower values of
1.5
3
3.5
sat
point
2
4
50%
45%
40%
35%
30%
25%
20%
15%
10%
40%
35%
30%
25%
20%
15%
10%