HSP50214B Ver la hoja de datos (PDF) - Renesas Electronics
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HSP50214B Datasheet PDF : 62 Pages
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HSP50214B
TABLE 4. HALFBAND FILTER COEFFICIENTS
COEFFICIENTS
C0
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
HALFBAND #1
- 0.031303406
0.000000000
0.281280518
0.499954224
0.281280518
0.000000000
- 0.031303406
HALFBAND #2
0.005929947
0.000000000
-0.049036026
0.000000000
0.29309082
0.499969482
0.29309082
0.000000000
-0.049036026
0.000000000
0.005929947
HALFBAND #3
-0.00130558
0.000000000
0.012379646
0.000000000
-0.06055069
0.000000000
0.299453735
0.499954224
0.299453735
0.000000000
-0.06055069
0.000000000
0.012379646
0.000000000
-0.00130558
HALFBAND #4
0.000378609
0.000000000
-0.003810883
0.000000000
0.019245148
0.000000000
-0.069904327
0.000000000
0.304092407
0.500000000
0.304092407
0.000000000
-0.069904327
0.000000000
0.019245148
0.000000000
-0.003810883
0.000000000
0.000378609
HALFBAND #5
-0.000347137
0.000000000
0.00251317
0.000000000
-0.010158539
0.000000000
0.03055191
0.000000000
-0.081981659
0.000000000
0.309417725
0.500000000
0.309417725
0.000000000
-0.081981659
0.000000000
0.03055191
0.000000000
-0.010158539
0.000000000
0.00251317
0.000000000
-0.000347137
NOTE: While Halfband filters are typically selected starting with the last stage in the filter chain to give the maximum alias free bandwidth,
a higher throughput rate may be obtained using other filter combinations. See Application Note 9720, “Calculating Maximum
Processing Rates of the PDC”.
Depending on the number of halfbands used, PROCCLK
must operate at a minimum rate above the input sample
rate, fS, to the halfband. This relationship depends on the
number of multiplies for each of the halfband filter stages.
The filter calculations take 3, 4, 5, 6, and 7 multiplies per
input for HB1, HB2, HB3, HB4, and HB5 respectively. If we
keep the assumption that fS is the input sampling frequency,
then Equation 10 shows the minimum ratio needed.
fPROCCLK/fS ([(7)(HB5)(2HB5)+
(6)(HB4)(2(HB4 + HB5))+
(5)(HB3)(2(HB3+HB4+HB5))+
(4)(HB2)(2(HB2+HB3+ HB4+HB5))+
(3)(HB1)(2(HB1+HB2+HB3+HB4+HB5))]/2T
(EQ. 10)
where
HB1 = 1 if this section is selected and 0 if it is bypassed;
HB2 = 1 if this section is selected and 0 if it is bypassed;
HB3 = 1 if this section is selected and 0 if it is bypassed;
HB4 = 1 if this section is selected and 0 if it is bypassed;
HB5 = 1 if this section is selected and 0 if it is bypassed;
T = number of Halfband Filters Selected. The range for T is
from 0 to 5.
Examples of PROCCLK Rate Calculations
Suppose we enable HB1, HB3, and HB5. Using Figure 16,
HB1= 1, HB3 = 1, and HB5 = 1. Since stage 2 and stage 4
are not used, HB2 and HB4 = 0. PROCCLK must operate
faster than (7x2+5x4+3x8)/8 = 7.25 times faster than fS .
If all five halfbands are used, then PROCCLK must operate at
(7x2+6x4+5x8+4x16+3x32)/32 = 7.4375 times faster than fS .
255-Tap Programmable FIR Filter
The Programmable FIR filter can be used to implement real
filters with even or odd symmetry, using up to 255 filter taps,
or complex filters with up to 64 taps. The FIR filter takes
advantage of symmetry in coefficients by summing data
samples that share a common coefficient, prior to
multiplication. In this manner, two filter taps are calculated
per multiply accumulate cycle. Asymmetric filters cannot
share common coefficients, so only one tap per multiply
accumulate cycle is calculated. The filter can be effectively
bypassed by setting the coefficient C0 = 1 and all other
coefficients, CN = 0.
FN4450 Rev 4.00
May 1, 2007
Page 19 of 62
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