ACPR Measurement Method
Adjacent-channel power ratio
(ACPR) is used to characterize
the distortion of power amplifiers
and other subsystems for their
tendency to cause interference
with neighboring radio channels
or systems. The ACPR measure-
ment often is specified as the
ratio of the power spectral
several offset frequencies. For the
Cellular band (824 849 MHz
~
transmitter channel), the two
offsets are at ±885 kHz and
±1.98 MHz and the measurement
resolution bandwidth specified is
30 kHz. These offsets are at
±1.25 MHz and ±1.98 MHz for the
PCS band (1850 1910 MHz
~
density (PSD) of the CDMA main
channel to the PSD measured at
transmitter channel).
1.23 MHz
0
-10
-20
1st ACPR (dBc)
30 kHz
2nd ACPR (dBc)
30 kHz
-30
30 kHz
-40
30 kHz
st
st
1
ACPR-L
1
ACPR-U
-50
-60
-70
-80
Offset frequency
nd
nd
2
ACPR-U
2
ACPR-L
= 1.98 MHz
= 1.98 MHz
FREQUENCY (MHz)
Figure 16. CDMA Adjacent-Channel Power Ratio Measurement.
14
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