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TriQuint Semiconductor, Inc

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Page 13 of 15 May 2009

AP561

0.7-2.9 GHz WiMAX 8W Power Amplifier

2.5 – 2.7 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-PCB2500 measured and configured for 2.6GHz 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

Freq = 2.6 GHz, T= 25ºC

0

1

2

3

4

5

20

22

24

26

28

30

32

34

Output Power (dBm)

200mA

220mA

240mA

260mA

280mA

300mA

Efficiency vs. Output Average Power vs Icq

Freq = 2.6 GHz, T= 25ºC

0

5

10

15

20

25

30

20

22

24

26

28

30

32

34

Output Power (dBm)

200mA

220mA

240mA

260mA

280mA

300mA

Power Gain vs. Output Average Power vs. Icq

Freq = 2.6GHz, T= 25ºC

9

10

11

12

13

14

20

22

24

26

28

30

32

Output Power (dBm)

200mA

220mA

240mA

260mA

280mA

300mA

Power Gain vs.Frequency vs. Icq

Vcc = 12V, T= 25ºC

9

10

11

12

13

14

2.4

2.5

2.6

2.7

2.8

Frequency (GHz)

200mA

220mA

240mA

260mA

280mA

300mA

Icc vs. Output Average Power vs. Icq

Freq = 2.6 GHz, T= 25ºC

200

300

400

500

600

700

20

22

24

26

28

30

32

34

Output Power (dBm)

200mA

220mA

240mA

260mA

280mA

300mA