HSP50214A Datasheet, PDF (44/60 Pages) Intersil Corporation – Programmable Downconverter

HSP50214A
PDC Configuration
References
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 B.
The composite filter response, constrained primarily by half-
band filter 5 and the FIR filter, are shown in Figure 45.
For Intersil documents available on the web, see
http://www.intersil.com/
Intersil AnswerFAX [phone].
[1] HSP50210 Data Sheet, Intersil Corporation, AnswerFAX
Doc. No. 3652.
[2] Cellular Radio and Personal Communications: A Book of
Selected Readings, Theodore S. Rappaport, 1995 by
IEEE, Inc.
[3] AN9720 Application Note, Intersil Corporation, “Calcu-
lating Maximum Processing Rates of the PDC
(HSP50214A)”, AnswerFAX Doc. No. 99720.
[4] FO-007 Block Diagram of HSP50214.
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”.
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