GC5016 datasheet(81/88 Pages) TI

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GC5016

SLWS142G − JANUARY 2003 − REVISED NOVEMBER 2005

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18 5016 − CONFIGURATION SOFTWARE

18.1 CDMA2000

This section describes an example of the down-conversion filter response for CDMA2000 1X. The GC5016

configuration values were input sample rate of 78.643 MSPS, CIC decimation of eight, and PFIR decimation of four

for an overall decimation of 32, output rate of 2.4576 MSPS (2x chip rate), and 255 PFIR taps. The overall filter

response, including both the CIC and PFIR filters, is shown in Figure 33 and Figure 34. As seen in Figure 34 of the

transition region, the filter response meets the CDMA2000 1X stop-band rejection requirements of −50 dB at 750

kHz and −87 dB at 900 kHz.

−120

−100

−80

−60

−40

−20

−5

−4

−3

−2

−1

012345

Frequency − MHz

FILTER RESPONSE

FREQUENCY

Figure 33. CDMA2000 1X Filter Response

−120

−100

−80

−60

−40

−20

0.0

0.2

0.4

0.6

0.8

1.0

Frequency − MHz

FILTER RESPONSE

FREQUENCY

−87

dBc

−50 dbc

Figure 34. CDMA2000 1X Filter Response Transition Region with Spectral Mask

In transmit the input is presumed to operate at one sample per chip (1.2288 MHz), the PFIR interpolates by four and

uses a 192 tap filter that applies the phase predistortion, pulse shaping, adjacent channel rejection, and CIC roll-off

compensation. This is followed by a six stage CIC filter. The cmd5016 configuration file and filter taps are available

on the web.

GC5016 Datasheet(PDF) 81 Page - Texas Instruments

GC5016 Datasheet(HTML) 81 Page - Texas Instruments

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