AN4126 Datasheet, PDF (18/28 Pages) STMicroelectronics – The SPIRIT1 is a very low power RF transceiver

Transmitter parameter
Figure 12. 6 dB bandwidth measurement
AN4126
20
10
0
2-FSK, 500 kbps 250 kHz
6 dB bandwidth
-10
-20
-30
3.2.2
-40
-50
9.131E+08
9.136E+08
9.141E+08
6 dB bandwidth
9.146E+08
9.151E+08
Frequency [Hz]
9.156E+08
9.161E+08
9.166E+08
9.171E+08
AM13156v1
Digital modulation schemes peak output power
To measure the peak output power, center the spectrum analyzer on the required channel
and put the SPIRIT1 into modulated mode. Set the span about 5 times the 6 dB bandwidth
measurement, the RBW greater than the 6 dB bandwidth and the VBW equal to or greater
than the RBW. The maximum permitted peak conducted output power is 30 dBm (1 W). The
SPIRIT1 output power is lower than the maximum permitted output power. An external PA
can be used to reach the maximum output power.
To perform this measurement on the SPIRIT1, the cases with 2-FSK modulation, 500 kbps
data rate and 250 kHz frequency deviation are chosen. The span is set to 2 MHz (3 times
the 6 dB measured bandwidth), the RBW is set to 1 MHz (greater than the 6 dB bandwidth),
and the VBW equal to the RBW. The measured SPIRIT1 output power is 10 dBm. This
output power is lower than the maximum permitted output power. An external PA must be
used to reach the maximum output power.
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Doc ID 023299 Rev 1