NE5204AN View Datasheet(PDF) - Philips Electronics
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NE5204AN Datasheet PDF : 14 Pages
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Philips Semiconductors
Wide-band high-frequency amplifier
Product specification
NE/SA5204A
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:
IP2=POUT+IMR2
IP3=POUT+IMR3/2
where POUT is the power level in dBm of each of a pair of equal
level fundamental output signals, IP2 and IP3 are the second and
third order output intercepts in dBm, and IMR2 and IMR3 are the
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slopes, and the intercept description is no longer valid.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 IP2 and IP3 at output levels well below 1dB
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 NE/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.
2.0
1.9
1.8
TA = 25oC
1.7
VCC = 6V .
1.6
1.5
1.4
1.3 ZO = 75Ω
1.2 ZO = 50Ω
1.1
1.0
101
2
4 6 8 102 2
4 6 8103
FREQUENCY—MHz
a. Input VSWR vs Frequency
2.0
1.9
1.8
Tamb = 25oC
1.7
VCC = 6V
1.6
1.5
1.4
1.3 ZO = 75Ω
1.2
1.1 ZO = 50Ω
1.0
101
2
4 6 8 102 2
4 6 8103
FREQUENCY—MHz
b. Output VSWR vs Frequency
Figure 21. Input/Output VSWR vs Frequency
SR00213
+30
THIRD ORDER
+20
INTERCEPT POINT
1dB
+10
COMPRESSION POINT
2ND ORDER
INTERCEPT
POINT
0
FUNDAMENTAL
RESPONSE
-10
2ND ORDER
-20
RESPONSE
3RD ORDER
-30
RESPONSE
-40
-60 -50 -40 -30 -20 -10
0
INPUT LEVEL dBm
Figure 22.
+10 +20 +30 +40
SR00214
1992 Feb 25
11
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