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參數資料
| 型號： | LMV248 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Dual Band GSM Power Controller |
| 中文描述： | 雙頻GSM功率控制器 |
| 文件頁數： | 9/11頁 |
| 文件大?。?/td> | 289K |
| 代理商： | LMV248 |
Application Section
(Continued)
The LMV248 has separate inputs for the coupler/detector
feedback signal(s). These may be combined as a single
input when using a single coupler/detector that accommo-
dates both RF bands. When the two are combined as shown
in Figure 5 internal current sources are placed in parallel. To
maintain correct temperature compensation characteristics
for the applications circuit, an external biasing resistor, R'
should be added externally. For this arrangement, VfA, VfB,
and TC all are returned to a common supply, V
CC
.
Selecting Coupler/Detector
Coupler Calculations:
The applied Ramp voltage controls the RF power output.
Because of this the maximum Ramp voltage sets the mini-
mum attenuation that is allowed in the direction coupler used
to sense output power.
The basic equation is;
P
O
= V
rms2
/R
O
For peak detection it is;
The coupling factor, at maximum power, is defined as C
f
or,
Cf = (V
)
2
/2 x (P
outmax
x R
O
) for couplers that sense
peak power
The limit conditions for the maximum ramp and max power
out is,
V
rampmax
= 2.0V
P
outmax
= 2Watts
R
O
= 50
C
fdB
= 10 x log
10
[(1/2)(V
rampmax
)2/P
outmax
x R
O
)]
C
fdB
= 16.98dB
Attenuation in the directional coupler should be at least
17dB, to assure maximum power out.
General Device Equations
Calculation:
Let Vf be VfA or VfB as selected by BS. Let RVf be the
external series resistance from Vf to the Detector diode.
Voltage at the non-inverting terminal of A1 V
NI
= TC, since
current into A2’s input is small.
Voltage at the inverting terminal of A1 V
INV
= Vf -
[Ramp/(20k
)] x (RVf + 48.5k
)
Assuming the external series resistance for VfA and VfB is
<<
48.5k
:
Voltage at the inverting terminal of A1 V
INV
= Vf – 2.42 x
Ramp
Differential voltage at A1 inputs = V
NI
- V
INV
= TC - (Vf - 2.42
x Ramp) = 2.42 x Ramp - (Vf - TC).
Closed loop regulation of RF output power will force the
average differential voltage at A1 inputs to approach zero:
Average
Including the V
ramp
deadband and the device offset voltage,
the equation for the VfA, B vs. V
ramp
relationship becomes:
VfA, B = 2.42 x (V
ramp
-200mV) + TC - 80mV, all variables
being ground referenced DC voltages.
L
www.national.com
9
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PDF描述 |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LMV248LQ | 功能描述:IC CTROL DUAL BAND PWR 16-LLP RoHS:否 類別:RF/IF 和 RFID >> RF 電源控制器 IC 系列:- 標準包裝:3,000 系列:- RF 型:GSM 頻率:450MHz ~ 2GHz 特點:四頻帶 封裝/外殼:8-VFBGA 供應商設備封裝:8-MicroSMD（1.51x1.51） 包裝:帶卷 (TR) 其它名稱:LMV243BLX |
| LMV248LQX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Dual Band GSM Power Controller |
| LMV2F-3M4 | 制造商:BACO Controls Inc 功能描述: |
| LMV301 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Low Bias Current, 1.8V to 5V Single-Supply, Rail-to-Rail Operational Amplifier |
| LMV301MG | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風格:SMD/SMT 封裝 / 箱體:QFN-16 轉換速度:0.89 V/us 關閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
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