Specifications

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SLWS142J − JANUARY 2003 − REVISED AUGUST 2007
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18.2 WCDMA (UMTS)
This section describes an example of the down-conversion filter response for WCDMA. The GC5016 configuration
values were input sample rate of 122.88 MHz, a CIC and PFIR decimation of four each for an overall decimation of
16, output rate of 7.68 MSPS, and 255 PFIR taps. The overall filter response filter, including both the CIC and PFIR
filters, an optimized raised root cosine filter with α = 0.22, is shown in Figure 35 and Figure 36. The stop-band
attenuation is better than –80 dBc for frequencies more than 2.5 MHz from the band center.
−120
−100
−80
−60
−40
−20
0
−15 −10 −5 0 5 10 15
Frequency − MHz
Filter Response − dB
FILTER RESPONSE
vs
FREQUENCY
Figure 35. UMTS Filter Response
−120
−100
−80
−60
−40
−20
0
012345
Frequency − MHz
Filter Response − dB
FILTER RESPONSE
vs
FREQUENCY
Figure 36. UMTS Filter Response Transition Region
The cmd5016 configuration file and filter taps are available on the web.