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参数资料
| 型号： | WE905 |
| 厂商： | Electronic Theatre Controls, Inc. |
| 英文描述： | 0.1 - 1GHx Single Chip FM Transceiver |
| 中文描述： | 0.1 - 1GHx单芯片FM收发器 |
| 文件页数： | 17/39页 |
| 文件大小： | 623K |
| 代理商： | WE905 |
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Winceiver WE904/WE905
WiNEDGE & WiRELESS
0.1 - 1GHz Single Chip FM Transceiver
2003 WiNEDGE & WiRELESS PTE LTD
Page 24
Rev Date: 2003 May 27
AFC CORRECTION RANGE
The AFC correction range should be at least 2 x crystal frequency tolerance: including temperature,
aging and tuning.
The steps to select components for the desire correction range are:
1.
Determine C1, C2 and C3*,
where C3* is the equivalent capacitance of C3//TC1//D1.
The choice of C1, C2 and C3* depends on the crystal load capacitance and drive level.
In figure above, the expected load capacitance of the 12.0MHz crystal is 18pF. The load capacitance
presented by the circuit is approximately created by the series combination of C1, C2 and C3*.
Choice of C1 and C2 are affected by the crystal drive level. E.G. for a load capacitance of 18pF:
Drive level
0.1uW
0.1mW
C1, C2
82pF
47pF
C3*
27pF
56pF
2.
Determine the variation in C3* ( C3*) to provide correction range
This can be done experimentally by adjusting a trimmer capacitor or by calculation if the
characteristics of the crystal are known.
3.
Select varactor diode D1
Select a varactor that its change in capacitance from 2.5V to 0.1V is the slightly greater than C3*.
The varactor use in the above AFC circuit has a capacitance of 10pF at 2.5V and 25pF at 0.1V. It
gives an AFC correction range of +/- 20ppm.
4.
Select trimmer TC1
Select trimmer cap TC1 to correct the initial tolerance of the crystal.
The trimmer capacitor in above AFC circuit varies from 4pF to 20pF and gives a tuning range of +/-
30ppm.
5.
Select C3
If the mid value of D1 (~16pF) and TC1 (~9pF) is lesser than C3*, then C3 (~2pF) is added to make
up to the required C3*.
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相关代理商/技术参数 |
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|---|---|
| WE9104 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Pulse Telephone Dialer |
| WE9110 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Pulse Telephone Dialer |
| WE9140 | 制造商:WINBOND 制造商全称:Winbond 功能描述:TONE/PULSE SWITCHABLE DIALER WITH REDIAL |
| WE9140A | 制造商:WINBOND 制造商全称:Winbond 功能描述:TONE/PULSE SWITCHABLE DIALER WITH REDIAL |
| WE9140B | 制造商:WINBOND 制造商全称:Winbond 功能描述:TONE/PULSE SWITCHABLE DIALER WITH REDIAL |
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