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参数资料
| 型号： | W9009 |
| 元件分类： | 无绳电话/电话 |
| 英文描述： | TELECOM, CORDLESS, BASEBAND CIRCUIT, PQFP32 |
| 封装： | TQFP-32 |
| 文件页数： | 7/20页 |
| 文件大小： | 526K |
| 代理商： | W9009 |
Lucent Technologies Inc.
15
Data Sheet
September 1999
Cordless Telephony—Version 2.0
W9009 RF Transceiver for 900 MHz
Testing and Application of the W9009 (continued)
Receive LNA and Downconverter (continued)
The values of L3, R2, C5, and C7 in the application circuit differ from the test circuit for two reasons. The first is that
typical ceramic 10.7 MHz bandpass filters have spurious responses several megahertz from the desired passband,
and these components may be used to create a bandpass filter which suppresses these spurious peaks. The sec-
ond is that additional gain is achievable by loading MXOUT with a higher impedance and performing a reactive
impedance transformation to the 330
impedance of the ceramic filter. Using R2 of 560 gives the higher gain at
MXOUT, and L3, C5, and C7 values of 1.0
H, 200 pF, and 56 pF, respectively, creates the impedance transformer
to 330
.
Downconverter image rejection is similar in theory to upconverter image rejection, but different qualitatively, so
some effort will be taken to explain here. On transmit, the IF and LO signals are mixed to produce signals centered
about (LO – IF) and (LO + IF). The desired sideband is passed, and the image is suppressed.
On receive, the desired signal and LO are separated by the IF frequency, just as on transmit. Thus the desired sig-
nal is at either (LO – IF) or (LO + IF). However, not just one of these but both signals are translated to IF. In other
words, the image is translated to IF along with the desired signal—whatever is there, whether noise or a signal sim-
ilar to the desired or a totally unrelated interferer. Once the image is translated to the IF, there is no way to get rid of
it. If the IF is high enough, a filter can be used to suppress the image before downconversion.
With the W9009, the image is always within or sufficiently near the passband of the RF front end filter that another
way to suppress the image is required. Assume the RF inputs to the downconverter are two tones, A at the LSB
and B at the USB, written as [ Acos(LO – IF) + Bcos(LO + IF) ]. Since quadrature signals are required of both the
LO and RF inputs, the input is applied to a phase shifter with output [ Asin(LO – IF) + Bsin(LO + IF) ]. (This phase
shift is actually performed at the IF output, but the math is more straightforward if done at the input.) The quadra-
ture LO signals are cos(LO) and sin(LO). Applying the cosine inputs and LO to one mixer and ignoring the terms at
(2LO ± IF) gives [ Acos(IF) + Bcos(IF) ] at its output. Applying the sine inputs and LO to the other mixer and ignor-
ing the terms at (2LO ± IF) gives [ –Acos(IF) + Bcos(IF) ] at its output. Summing the two mixer outputs reinforces
the B term from the USB and cancels the A term from the LSB. Inverting the sine LO input gives [ Acos(IF) –
Bcos(IF) ] at the mixer output, which allows the B term from the USB to be canceled and the A term from the LSB
to be reinforced.
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相关代理商/技术参数 |
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| W9011M | 制造商:Pulse Electronics Corporation 功能描述:11 SMA Female to I-Pex Cable Assembly |
| W9015 | 制造商:Pulse 功能描述:15"R-SMAFEMALETOI-PEXCABLEASSEMBLY - Bulk 制造商:Pulse Electronics Corporation 功能描述:15 R-SMA Female to I-Pex Cable Assembly |
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