HSP50214B_07 Datasheet, PDF (45/62 Pages) Intersil Corporation – Programmable Downconverter

HSP50214B
PDC Configuration
For this example, the PDC is configured as follows:
CLKIN: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39MHz
Mode: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gated
Input Format: . . . . . . . . . . . . . As required by Digital Source
Carrier NCO Fc: . . . . . . . . As determined by Channel Freq.
Carrier NCO Phase Offset: . . . . . . . . . . . . . . . . . . . . . . . . .0
Carrier NCO Offset Frequency: . . . . . . . . . . . . . . . .Disabled
CIC Filter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Enabled
Decimation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
PROCCLK: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28MHz
Half Band Filters: . . . . . . . . . . . . . . . . . . HB3 and 5 Enabled
FIR Filter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gsmtemp file
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . f_S = 541.667kHz
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Decimation = 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Passband: 90kHz
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transition Band: 25kHz
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Passband Atten: 3dB
. . . . . . . . . . . . . . . . . . . . . . . . . Stop Band Atten: 111.25713
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .FIR Order: 90
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FIR Symmetry: Even
Resampling Filter: . . . . . . . . . . . . . . . . . . . . . . HB1 Enabled
The basis for this configuration is:
Sampling Rate: Select a high rate PROCCLK
Output Rate: 1.083MHz (4x Bit Rate; 8x Baud Rate)
CIC Filtering: Primarily Rate Reduction (39/18 = 2.166MHz).
HB Filtering: Flat passband with rate reduction by 4 - low
enough (541.66kHz) for sufficient FIR Taps to be used.
FIR Filtering: Primary shaping filter/set final out of band
suppression.
Polyphase/HalfBand Filtering: Interpolate by two to output
8x baud rate or 4x bit rate.
The CIC and halfband filter responses are shown in Figures
48A and 48B.
The composite filter response constrained primarily by
halfband filter 5 and the FIR filter, are shown in Figure 48C
and 48D.
For a more detailed discussion of design approaches and
trades when designing with the PDC, refer to AN9720 [3],
“Calculating the Maximum Processing Rates of the PDC”.
References
For Intersil documents available on the web, see
www.intersil.com/
[1] HSP50210 Data Sheet, Intersil Corporation, FN3652.
[2] Cellular Radio and Personal Communications: A Book
of Selected Readings, Theodore S. Rappaport, 1995 by
IEEE, Inc.
[3] AN9720 Application Note, Intersil Corporation,
“Calculating Maximum Processing Rates of the PDC
(HSP50214B)”.
[4] FO-007 Block Diagram of HSP50214.
45
FN4450.4
May 1, 2007