GC5018_06 Datasheet, PDF (15/134 Pages) Texas Instruments – 8-CHANNEL WIDEBAND RECEIVER

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3.2 DDC Organization
GC5018
8-CHANNEL WIDEBAND RECEIVER
SLWS169A – MAY 2005 – REVISED NOVEMBER 2005
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18
4 to 2 (complex) or
18
4 to 1 (real) switch
CDMA DDC A
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or 1 UMTS DDC
Output
Interface
4 to 2 (complex) or
4 to 1 (real) switch
CDMA DDC B
DDC0
DDC1
DDC2
DDC3
DDC4
DDC5
DDC6
DDC7
Figure 3-12. DDC Organization for Single Length Filter Mode
The GC5018 provides downconversion for up to 8 UMTS receive channels, 16 CDMA2000 receive
channels or 16 TD-SCDMA receive channels. Downconversion channels are organized into 8 DDC blocks.
Each individual DDC block provides 2 CDMA2000 or 2 TD-SCDMA DDC channels, A and B, or 1 UMTS
channel.
Both CDMA DDC channels in a DDC block can be independently tuned, though they would likely be used
as diversity pairs and tuned to the same frequency. Filter coefficients are shared between the two CDMA
DDC channels within a block.
Two adjacent DDC blocks (for example, DDC0 and DDC1) can be strapped together to form a single
UMTS DDC channel with double-length final pulse shaping filtering. The GC5018 can therefore provide 4
UMTS DDC channels with double-length final PFIR filtering as shown in the following diagram.
RECEIVE DIGITAL SIGNAL PROCESSING
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