Specifications and information are subject to change without notice

WJ Communications, Inc

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Page 6 of 8 May 2008

AP561

2.3-2.9 GHz WiMAX 8W Power Amplifier

2.3 – 2.9 GHz Application Note: Changing Icq Biasing Configurations

The AP561 can be configured to operate with lower bias current by varying the bias-adjust resistor R2. (Table 1) The

recommended circuit configurations shown previously in this datasheet have the device operating with a 300 mA as the

upon the efficiency of the device, but degrade the EVM performance. Measured data shown in the plots below represents the

AP561 measured and configured for 2.4 GHz applications. It is expected that variation of the bias current for other frequency

applications will produce similar performance results.

Table 1 : Reduced Current Operation

Icq

(mA)

R2

(Ω)

(V)

(V)

300

330

5

2.85

280

336

5

2.81

260

240

5

2.78

240

343

5

2.76

220

348

5

2.73

200

351

5

2.71

EVM vs. Output Average Power vs. Icq

f=2.4 GHz

0

1

2

3

4

28

29

30

31

32

Pout (dBm)

200mA

220mA

240mA

260mA

280mA

300mA

Efficiency vs. Output Average Power vs Icq

f=2.4 GHz,

8

10

12

14

16

18

28

29

30

31

32

Pout (dBm)

200mA

220mA

240mA

260mA

280mA

300mA

r