ACPM-7813 データシートの表示（PDF） - HP => Agilent Technologies

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ACPM-7813

CDMA/AMPS Power Amplifier Module

HP => Agilent Technologies 

ACPR Test Results using Spectrum Analyzer

REF 42.8 dBm AT 30 dB

Mkr 836 MHz

35.42 dBm

RBW = 1.0 MHz

RBW = 300 kHz

RBW = 30 kHz

Center 836 MHz

VBW 100 kHz

Figure 21. Example ACPR measurement using Spectrum Analyzer.

Span 5.000 MHz

SWP 2.00 sec

The meaning of 16 dB

The accurate ACPR measurement

using Spectrum Analyzer needs

to consider the normalization

factor that is dependent on the

Resolution Bandwidth, RBW,

settings. The above figure (mea-

surement shown at 836 MHz for

general example) shows a com-

parison of the different ACPR

measurement results as a func-

tion of various RBW values. As

the RBW is reduced, less power is

captured during the measure-

ment and consequently the

channel power is recorded as a

smaller value. For example, if the

main channel power is measured

as 28 dBm in a 1.23 MHz band-

width, its power spectral density

is 28 dBm/1.23 MHz, which can

be normalized to 11.87 dBm/

30 kHz. The equation used to

calculate the normalization factor

of power spectral density is:

Normalization Factor =

10log[Normalization BW/Current BW

(Spectrum Analyzer RBW)]

= 10log[1.23X106/30X103]

= 16.13 dB

Since the ACPR in an IS95

system is specified in a 1.23 MHz

bandwidth, a channel power that

is measured using a different

RBW, can be normalized to

reflect the channel power as if it

was measured in a 1.23 MHz

bandwidth. The difference in

channel power measured in

30 kHz bandwidth and the

channel power measured in a

1.23 MHz bandwidth is 16 dB.

16

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