RMPA2259 View Datasheet(PDF) - Fairchild Semiconductor
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RMPA2259 Datasheet PDF : 11 Pages
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Efficiency Improvement Application
In addition to high-power/low-power bias modes, the
efficiency of the PA module can be significantly increased
at backed-off RF power levels by dynamically varying the
supply voltage (Vcc) applied to the amplifier. Since mobile
handsets and power amplifiers frequently operate at 10–
20dB back-off, or more, from maximum rated linear power,
battery life is highly dependent on the DC power consumed
at antenna power levels in the range of 0 to +16dBm. The
reduced demand on transmitted RF power allows the PA
supply voltage to be reduced for improved efficiency, while
still meeting linearity requirements for CDMA modulation
with excellent margin. High-efficiency DC-DC converters
are now available to implement switched-voltage operation.
The following charts show measured performance of the
PA module in low-power mode (Vmode = +2.0V) at
+16dBm output power and over a range of supply voltages
from 3.4V nominal to 1.2V. Power-added efficiency is more
than doubled from 9.5 percent to nearly 25 percent (Vcc =
1.2V) while maintaining a typical ACLR1 of -46dBc and
ACLR2 of approximately -60dBc.
Operation at even lower levels of Vcc supply voltage are
possible with a further restriction on the maximum RF
output power. As shown below, the PA module can be
biased at a supply voltage of as low as 0.7V with an
efficiency as high as 10–12 percent at +8dBm output
power. Excellent signal linearity is still maintained even
under this low supply voltage condition.
Performance Data (continued)
Low-Power Mode (Po = +16dBm)
RMPA2259 W-CDMA 4x4mm2 PAM
Vref = 2.85V, Pout = 16dBm
30
29
28
27
VCC = 3.4V
26 VCC = 3.0V
25 VCC = 2.0V
VCC = 1.5V
26
VCC = 1.2V
23
22
21
20
1900
1920
1940
1960
FREQUENCY (MHz)
1980
2000
Figure 5.
RMPA2259 W-CDMA 4x4mm2 PAM
Vref = 2.85V, Pout = 16dBm
-35
-37
-39
-41
VCC = 3.4V
-43
VCC = 2.0V
VCC = 1.5V
-45
VCC = 1.2V
-47
VCC = 3.0V
-49
-51
-53
-55
1900
1920
1940
1960
FREQUENCY (MHz)
1980
2000
Figure 7.
RMPA2259 W-CDMA 4x4mm2 PAM
Vref = 2.85V, Pout = 16dBm
30
25
VCC = 1.2V
20
VCC = 1.5V
VCC = 2.0V
15
10 VCC = 3.0V
VCC = 3.4V
5
1900
1920
1940
1960
FREQUENCY (MHz)
Figure 6.
1980
2000
RMPA2259 W-CDMA 4x4mm2 PAM
Vref = 2.85V, Pout = 16dBm
-50
-52
-54
-56
-58
VCC = 1.2V
-60
-62
VCC = 1.5V
VCC = 2.0V
-64 VCC = 3.0V
VCC = 3.4V
-66
-68
-70
1900
1920
1940
1960
FREQUENCY (MHz)
1980
Figure 8.
2000
©2005 Fairchild Semiconductor Corporation
4
RMPA2259 Rev. E
www.fairchildsemi.com
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