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參數資料
| 型號： | AD8314-EVAL |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 100 MHz-2500 MHz 45 dB RF Detector/Controller |
| 中文描述： | 100兆赫，2500兆赫45分貝射頻檢測器/控制器 |
| 文件頁數： | 12/16頁 |
| 文件大小： | 274K |
| 代理商： | AD8314-EVAL |
AD8314
–12–
REV. 0
of the AD8314 to resistively divide the input signal being applied
to the input. This has the advantage of very little power being
“tapped off” in RF power transmission applications.
Table II. Recommended Components for X1 and X2 in
Figure 32b
Frequency
(GHz)
Voltage Gain
(dB)
X1
X2
52.3
39 nH
15 nH
3.9 nH
0.1
0.9
1.9
2.5
Short
33 nH
10 nH
1.5 pF
11.8
7.8
2.55
Increasing the Logarithmic Slope in Measurement Mode
The nominal logarithmic slope of 21.5 mV/dB (see Figure 7 for
the variation of slope with frequency) can be increased to an
arbitrarily high value by attenuating the signal between V_UP
and VSET as shown in Figure 33. The ratio R1/R2 is set using
the equation
R
1/
R
2 = (
New Slope/Original Slope
) – 1
In the example shown, two 5 k
resistors combine to change the
slope at 1900 MHz from 20 mV/dB to 40 mV/dB. The slope can
be increased to higher levels. This will, however, reduce the usable
dynamic range of the device.
AD8314
R1
5k
V
V_UP
VSET
40mV/dB
@ 1900MHz
R2
5k
V
Figure 33. Increasing the Output Slope
Effect of Waveform Type on Intercept
Although specified for input levels in dBm (dB relative to 1 mW),
the AD8314 fundamentally responds to voltage and not to power.
A direct consequence of this characteristic is that input signals of
equal rms power but differing crest factors will produce different
results at the log amp’s output.
The effect of differing signal waveforms is to shift the effective
value of the intercept upwards or downwards. Graphically, this
looks like a vertical shift in the log amp’s transfer function. The
logarithmic slope, however, is not affected. For example, consider
the case of the AD8314 being alternately fed by an unmodulated
sine wave and by a single CDMA channel of the same rms power.
The AD8314’s output voltage will differ by the equivalent of
3.55 dB (70 mV) over the complete dynamic range of the device
(the output for a CDMA input being lower).
Table III shows the correction factors that should be applied to
measure the rms signal strength of a various signal types. A
sine wave input is used as a reference. To measure the rms power
of a square wave, for example, the mV equivalent of the dB value
given in the table (20 mV/dB times 3.01 dB) should be subtracted
from the output voltage of the AD8314.
Table III. Shift in AD8314 Output for Signals with Differing
Crest Factors
Correction Factor
(Add to Measured
Input Level)
Signal Type
Sine Wave
Square Wave
GSM Channel (All Time Slots On)
CDMA Channel (Forward Link,
9 Channels On)
CDMA Channel (Reverse Link)
PDC Channel (All Time Slots On)
0 dB
–3.01 dB
0.55 dB
3.55 dB
0.5 dB
0.58 dB
Mobile Handset Power Control Examples
Figure 34 shows a complete power amplifier control circuit for
a dual mode handset. This circuit is applicable to any dual
mode handset using TDMA or CDMA technologies. The
PF08107B (Hitachi) is driven by a nominal power level of
+3 dBm. Some of the output power from the PA is coupled off
using an LDC15D190A0007A (Murata) directional coupler.
This has a coupling factor of approximately 19 dB for its lower
frequency band (897.5
±
17.5 MHz) and 14 dB for its upper band
(1747.5
±
37.5 MHz) and an insertion loss of 0.38 dB and 0.45dB
respectively. Because the PF08107B transmits a maximum power
level of +35 dBm, additional attenuation of 15 dB is required
before the coupled signal is applied to the AD8314.
1
2
3
4
ENBL
RFIN
AD8314
8
7
6
5
VSET
FLTR
VPOS
COMM
V UP
+V
S
2.7V
VSET
0V–1.1V
PF081807B
(HITACHI)
PIN BAND 1
+3dBm
PIN BAND 2
+3dBm
1000pF
0dBm
MAX
+V
S
ATTN
15dB
V DN
C
F
220pF
POUT
BAND 2
+32dBm MAX
POUT BAND 1
+35dBm MAX
4.7
m
F
TO
ANTENNA
49.9
V
7
8
5
1
4
3
2
6
LDC15D190A0007A
BAND
SELECT
0V/2V
3.5V
V
CTL
V
APC
0.1
m
F
52.3
V
Figure 34. A Dual Mode Power Amplifier Control Circuit
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相關代理商/技術參數 |
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|---|---|
| AD8315 | 制造商:AD 制造商全稱:Analog Devices 功能描述:50 dB GSM PA Controller |
| AD8315_06 | 制造商:AD 制造商全稱:Analog Devices 功能描述:50 dB GSM PA Controller |
| AD8315ACHIPS | 制造商:AD 制造商全稱:Analog Devices 功能描述:50 dB GSM PA Controller |
| AD8315ACP-EVAL | 制造商:Analog Devices 功能描述:EVAL BOARD GSM PA CONTR AD8 |
| AD8315ACP-REEL | 制造商:Analog Devices 功能描述: |
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