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參數資料
| 型號： | LMV225TL |
| 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, PBGA4 |
| 封裝： | 1 X 1 MM, 0.60 MM HEIGHT, LEAD FREE, MO-211BA, MICRO SMD-4 |
| 文件頁數： | 19/21頁 |
| 文件大小： | 1090K |
| 代理商： | LMV225TL |
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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相關代理商/技術參數 |
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| LMV225TL/NOPB | 功能描述:射頻檢測器 Sgl Rf Detector Cdma & 3G 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 |
| LMV225TLEVAL | 功能描述:電源管理IC開發工具 LMV225TL EVAL BOARD RoHS:否 制造商:Maxim Integrated 產品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LMV225TLX | 制造商:Texas Instruments 功能描述:RF Power Detector for CDMA and WCDMA 4-Pin uSMD T/R |
| LMV225TLX/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 |
| LMV225UR/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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