AP562_15 Datasheet, PDF (6/8 Pages) TriQuint Semiconductor – 3.3-3.8 GHz WiMAX 8W Power Amplifier

AP562
3.3-3.8 GHz WiMAX 8W Power Amplifier
3.4 – 3.6 GHz Application Note: Changing Icq Biasing Configurations
The AP562 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 400 mA as the
quiescent current (I_CQ). This biasing level represents a tradeoff in terms of EVM and efficiency. Lowering I_CQ will improve
upon the efficiency of the device, but degrade the EVM performance. Measured data shown in the plots below represents the
AP562 measured and configured for 3.5 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
R2 V_PD
I_REF
(mA) (Ω) (V) (V)
400 270 5
2.92
350 275 5
2.88
300 320 5
2.83
250 380 5
2.8
200 473 5
2.73
150 616 5
2.66
100 857 5
2.6
EVM vs. Output Average Power vs. Icq
4
f=3.5 GHz
3
2
1
100mA 150mA 200mA 250mA
300mA 350mA 400mA
0
28
29
30
31
32
Pout (dBm)
Efficiency vs. Output Average Power vs Icq
24
f=3.5 GHz
100mA 150mA 200mA 250mA
300mA 350mA 400mA
20
16
12
8
28
29
30
31
32
Pout (dBm)
Specifications and information are subject to change without notice
TriQuint Semiconductor, Inc • Phone [phone] • FAX: [phone] • e-mail: [e-mail] • Web site: www.TriQuint.com
Page 6 of 8 May 2009