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參數(shù)資料
| 型號： | LMV225SD |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 無繩電話/電話 |
| 英文描述： | RF Power Detector for CDMA and WCDMA |
| 中文描述： | TELECOM, CELLULAR, RF AND BASEBAND CIRCUIT, DSO6 |
| 封裝： | 2.20 X 2.50 MM, 0.80 MM HEIGHT, LLP-6 |
| 文件頁數(shù)： | 19/21頁 |
| 文件大?。?/td> | 1090K |
| 代理商： | LMV225SD |
Application Notes
(Continued)
All gain cell outputs are AM-demodulated with a peak detec-
tor and summed together. This results in a logarithmic func-
tion. The logarithmic range is about:
20 · n · log (A)
where,
n = number of gain cells
A = gain per gaincell
Figure 9
shows a logarithmic function on a linear scale and
the piecewise approximation of the logarithmic function.
Figure 10
shows a logarithmic function on a logarithmic
scale and the piecewise approximation of the logarithmic
function.
The maximum error for this approximation occurs at the
geometric mean of a gain section, which is e.g. for the third
segment:
(9)
The size of the error increases with distance between the
thresholds.
LAYOUT CONSIDERATIONS
For a proper functioning part a good board layout is neces-
sary. Special care should be taken for the series resistance
R
(
Figure 1
) that determines the attenuation. For high re-
sistor values the parasitic capacitance of the resistor may
significantly impact the realized attenuation. The effective
attenuation will be lower than intended. To reduce the para-
sitic capacitance across resistor R
1
, this resistor can be
composed of several components in series instead of using
a single component.
20076020
FIGURE 8. Gain Cell
20076021
FIGURE 9. Log-Function on Lin Scale
20076022
FIGURE 10. Log-Function on Log Scale
L
www.national.com
19
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LMV225SD/NOPB | 功能描述:射頻檢測器 Sgl Rf Detector W/ LLP RoHS:否 制造商:Skyworks Solutions, Inc. 配置: 頻率范圍:650 MHz to 3 GHz 最大二極管電容: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:SC-88 封裝:Reel |
| LMV225SDEVAL | 功能描述:射頻開發(fā)工具 LMV225SD EVAL BOARD RoHS:否 制造商:Taiyo Yuden 產(chǎn)品:Wireless Modules 類型:Wireless Audio 工具用于評估:WYSAAVDX7 頻率: 工作電源電壓:3.4 V to 5.5 V |
| LMV225SDX | 制造商:Texas Instruments 功能描述:RF Power Detector for CDMA and WCDMA 6-Pin LLP EP T/R |
| LMV225SDX/HALF | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述: |
| LMV225SDX/NOPB | 功能描述:射頻檢測器 RoHS:否 制造商:Skyworks Solutions, Inc. 配置: 頻率范圍:650 MHz to 3 GHz 最大二極管電容: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:SC-88 封裝:Reel |
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