RMPA1959 데이터 시트보기 (PDF) - Fairchild Semiconductor

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RMPA1959

PCS 3.4V CDMA & CDMA2000-1X PowerEdge™ Power Amplifier Module

Fairchild Semiconductor 

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 10–20

dB 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 +16 dBm. 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 figures 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 down to 1.2V. Power-added efficiency is

more than doubled from 10 percent to nearly 25 percent

(Vcc = 1.2V) while maintaining a typical ACPR1 of –52dBc

and ACPR2 of less than –61dBc.

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.

30

29

28

27

26

25

24

23

22

21

20

1840

-40

-42

-44

-46

-48

-50

-52

-54

-56

-58

-60

1840

RMPA1959 PCS 4x4mm2 PAM

Vref = 2.85V, Pout=16dBm

Vcc=3.4V

Vcc=2.0V

Vcc=1.5V

Vcc=1.2V

Vcc=3.0V

1860

1880

1900

Frequency (MHz)

1920

RMPA1959 PCS 4x4mm2 PAM

Vref = 2.85V, Pout=16dBm

Vcc=1.2V

Vcc=1.5V

Vcc=2.0V

Vcc=3.0V

Vcc=3.4V

1860

1880

1900

Frequency (MHz)

1920

35

30

25

20

15

10

5

1840

RMPA1959 PCS 4x4mm2 PAM

Vref = 2.85V, Pout=16dBm

Vcc=1.2V

Vcc=1.5V

Vcc=2.0V

Vcc=3.4V

Vcc=3.0V

1860

1880

1900

Frequency (MHz)

1920

-55

-57

-59

-61

-63

-65

-67

-69

-71

-73

-75

1840

RMPA1959 PCS 4x4mm2 PAM

Vref = 2.85V, Pout=16dBm

Vcc=1.5V

Vcc=1.2V

Vcc=2.0V

Vcc=3.4V

Vcc=3.0V

1860

1880

1900

Frequency (MHz)

1920

©2004 Fairchild Semiconductor Corporation

RMPA1959 Rev. D

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