AD8341

Rev. 0 | Page 16 of 20

As the output power drops, the noise floor, measured in dBm in

1 MHz BW at 50 MHz carrier offset, drops slightly.

–30

–80

–75

–70

–65

–60

–55

–50

–45

–40

–35

–30

–25

–20

–15

–10

–5

0

5

OUTPUT POWER (dBm)

–50

–55

–60

–65

–70

–75

–80

–85

–90

–95

–100

ACPR 5MHz OFFSET

ACPR 10MHz OFFSET

NOISE –50MHz OFFSET

Figure 39. AD8341 ACPR and Noise vs. Output Power;

Single-Carrier WCDMA (Test Model 1-64 at 2140 MHz)

Figure 40 shows how output power, ACPR, and noise vary with

together and are varied from 0.5 V to 50 mV.

0

–50

–45

–40

–35

–30

–25

–20

–15

–10

–5

0

0.1

0.2

0.3

0.4

0.5

IQ CONTROL VOLTAGE

–40

–45

–50

–55

–60

–65

–70

–75

–80

–85

–90

OUTPUT POWER dBm

ACPR 10MHz OFFSET

NOISE –50MHz OFFSET

ACPR 5MHz OFFSET

Single-Carrier WCDMA (Test Model 1-64 at 2140 MHz)

In this case, adjacent channel power ratio remains constant as

the (noise dominated) alternate channel power degrades

roughly 1-for-1 with output power. As the I and Q control volt-

age drops, the noise floor again drops slowly.