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| 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： | 36/39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 6
Rev Date: 2003 May 27
FUNCTIONAL DESCRIPTION
The receive section consists of several major function blocks, including a switchable RF input
attenuator (PAD), quadrature down-conversion mixer, differential-to-single-ended conversion, variable
gain amplifiers (VGAs), PLL synthesizer/ voltage controlled oscillator (VCO), I/Q low-pass filters, DC
offset correction circuitry, quadrature up-conversion mixer, IF filter, P/D FM demodulator.
The transmit section consists of a PLL synthesizer, direct frequency modulated voltage controlled
oscillator (VCO), and a RF power amplifier (PA).
Additionally, the device contains a reference crystal oscillator, an automatic frequency control (AFC)
circuitry and associated reference frequency synthesizer.
A functional block diagram of the IC is shown in page 4. The following sections give details of each
functional block.
ZERO IF RECEIVER
The receiver section of the WE904/905 utilizes a quadrature mixer in a direct-conversion, zero-
intermediate frequency (zero-IF) approach. After quadrature down-conversion and baseband filtering,
a quadrature mixer up-converts the complex baseband signal to an intermediate frequency (IF) for
demodulation.
Direct conversion to zero-IF has several advantages over super-heterodyne approaches. First, the
image frequency is eliminated because the IF is zero. Second, the use of active, low pass, filters
provide a high level of integration, while eliminating the need for external IF filters and IF
transformers.
A description of each major receive function block follows:
RF Input Attenuator Pad
A switchable 0/-10dB attenuator pad allows high signal level capability at the RF Input of the receiver.
This pad is located prior to the quadrature mixer (down-conversion) and can be either manually
controlled via the 3-wire interface, or automatically controlled via the AGC section of the device.
Down-Conversion Quadrature Mixer
The main advantage of the quadrature mixer is its ability to translate the RF frequency directly to a
zero-IF, thereby eliminating the image frequency. Consequently, the image filter before the RF input
to the WE904/905 can be eliminated. The design requirements for the duplexer and RF band pass
filter may also be relaxed. In addition, the quadrature mixer achieves a lower overall noise figure by
virtue of image frequency elimination.
The balanced mixers in the quadrature mixer are designed to closely track each other in both
amplitude and phase response. The quadrature LO signal is generated by direct division of the
receive VCO, thereby eliminating external phase shifting networks. Furthermore, for improved noise
immunity, all internal RF signal paths are fully differential, thereby providing common mode noise
rejection. The gain of the mixer can be adjusted via the 3-wire interface programming or automatically
controlled by AGC.
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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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