HSP43124SC-45 Intersil, HSP43124SC-45 Datasheet - Page 8

• Manufacturer Part Number: HSP43124SC-45
• Manufacturer: Intersil

Specifications of HSP43124SC-45

• Lead Free Status / RoHS Status: Not Compliant

NOTE: Figure 8 shows the loading of a data sample, X0, such
that it will be multiplied by a mix factor designated by M0. For
mix factor bit widths which are less than the input bit width,
SYNCMX may be asserted before SYNCIN if desired.
If the mix factor is generated by the Weaver Modulator ROM,
the mix factor must be specified on MXIN and SYNCMX one
SYNCIN before that which precedes the target data word
(see Figure 9).
Filter Compute Engine
The Filter Compute Engine centers around a multiply
accumulator which is used to perform the sum-of-products
required for a variety of filtering configurations. These
configurations include a cascade of up to 5 halfband filters, a
single symmetric filter of up to 256 taps, a single asymmetric
filter of up to 128 taps, or a cascade of halfband filters
followed by a programmable filter. The filter configuration is
specified by programming the Filter Configuration Register
(see Table 1).
SYCNMX/
SYNCMX
SYNCIN
SYNCIN
FIGURE 8. DATA/MIX FACTOR SYNCHRONIZATION FOR
FIGURE 9. DATA/MIX FACTOR SYNCHRONIZATION
SCLK
MXIN
SCLK
MXIN
DIN
DIN
SERIALLY INPUT MIX FACTORS
WEAVER
M0
LSB
LSB
LSB
SYNC LEADS DATA
SYNC LEADS DATA
X0
M0
8
MSB
MSB
MSB
LSB
LSB
LSB
X0
HSP43124
The cascade of up to five halfband filters is an efficient
decimating filter structure. Each fixed coefficient filter in the
chain introduces a decimation of two, and the aggregate
decimation rate of the entire halfband filtering stage is given
by:
DEC
Thus, a cascade of 3 halfband filters would decimate the
input sample stream by a factor of 8.
Figure 10A is a block diagram of the halfband filter section.
The normalized frequencies for each halfband stage is
labeled. Figure 10B is an illustration of a cascaded filter
composed of five halfband filters. The final stage filter output
is clocked at FCLK/32. Since the output of each filter is at
half the rate of the input, the five halfband filter passband
characteristics can be viewed on a single plot whose X axis
is normalized to the filter output clock rate. Notice that all
halfband filters, by design, have 120dB passbands that are
less than the output rate divided by 2. Since the alias profile
is well below -120dB in the filter passband, alias concerns
are eliminated. The frequency responses of the five filters
are presented graphically in Figure 10C and in tabular form
in Table 3. Notice that the 6dB passband bandwidth (F =
0.25) is identical for all five halfband filters. The width of the
transition band, however, is different for each filter. The
transition band for the fifth halfband filter, HB5, is the
narrowest while that for the first halfband filter, HB1, is the
widest. The cascade of the halfband filters always
terminates with HB5 and is preceded by filters in order of
increasing transition bandwidth. For example, if the
HSP43124 is configured to operate with three halfbands, the
chain of filters would consist of HB3 followed by HB4 and
terminated with HB5. If only one halfband is selected, HB5 is
used.
HB
= 2
(NUMBER OF HALFBAND FILTERS SELECTED)
(EQ. 1)