SA5204 Philips, SA5204 Datasheet - Page 11

• Manufacturer Part Number: SA5204
• Description: Wide-band high-frequency amplifier
• Manufacturer: Philips

Philips Semiconductors
intermodulation ratio is illustrated in Figure 22, which shows product
output levels plotted versus the level of the fundamental output for
two equal strength output signals at different frequencies. The upper
line shows the fundamental output plotted against itself with a 1dB to
1dB slope. The second and third order products lie below the
fundamentals and exhibit a 2:1 and 3:1 slope, respectively.
The intercept point for either product is the intersection of the
extensions of the product curve with the fundamental output.
The intercept point is determined by measuring the intermodulation
ratio at a single output level and projecting along the appropriate
product slope to the point of intersection with the fundamental.
When the intercept point is known, the intermodulation ratio can be
determined by the reverse process. The second order IMR is equal
to the difference between the second order intercept and the
fundamental output level. The third order IMR is equal to twice the
difference between the third order intercept and the fundamental
output level. These are expressed as:
where P
level fundamental output signals, IP
third order output intercepts in dBm, and IMR
1997 Nov 07
IP
IP
Wide-band high-frequency amplifier
2
3
=P
=P
OUT
OUT
OUT
+IMR
+IMR
is the power level in dBm of each of a pair of equal
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
2
3
/2
10
1
Z
Z
O
O
a. Input VSWR vs Frequency
= 75
= 50
T
V
2
A
CC
= 25
= 6V
o
4
FREQUENCY—MHz
C
+30
+20
+10
.
-10
-20
-30
-40
2
6 8
0
and IP
-60
10
2
THIRD ORDER
INTERCEPT POINT
COMPRESSION POINT
FUNDAMENTAL
3
RESPONSE
-50
2
are the second and
2
and IMR
Figure 21. Input/Output VSWR vs Frequency
1dB
-40
4
3
6 8
are the
-30
10
3
-20
INPUT LEVEL dBm
Figure 22.
11
-10
second and third order intermodulation ratios in dB. The
intermodulation intercept is an indicator of intermodulation
performance only in the small signal operating range of the amplifier.
Above some output level which is below the 1dB compression point,
the active device moves into large-signal operation. At this point the
intermodulation products no longer follow the straight line output
slopes, and the intercept description is no longer valid. It is therefore
important to measure IP
compression. One must be careful, however, not to select too low
levels because the test equipment may not be able to recover the
signal from the noise. For the SA5204A we have chosen an output
level of –10.5dBm with fundamental frequencies of 100.000 and
100.01MHz, respectively.
ADDITIONAL READING ON SCATTERING
PARAMETERS
For more information regarding S-parameters, please refer to
High-Frequency Amplifiers by Ralph S. Carson of the University of
Missouri, Rolla, Copyright 1985; published by John Wiley & Sons,
Inc.
“S-Parameter Techniques for Faster, More Accurate Network Design”,
HP App Note 95-1, Richard W. Anderson, 1967, HP Journal.
“S-Parameter Design”, HP App Note 154, 1972.
0
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
+10
10
1
Z
Z
O
O
2ND ORDER
RESPONSE
2ND ORDER
+20
INTERCEPT
3RD ORDER
RESPONSE
T
V
b. Output VSWR vs Frequency
= 75
= 50
amb
2
CC
POINT
= 6V
= 25
+30
2
4
and IP
o
FREQUENCY—MHz
C
6 8
+40
10
3
at output levels well below 1dB
2
2
4
Product specification
6 8
SA5204A
10
3
SR00213
SR00214