HSP50216KIZ Intersil, HSP50216KIZ Datasheet - Page 10

• Manufacturer Part Number: HSP50216KIZ
• Description: IC DOWNCONVERTER DGTL 4CH 196BGA
• Manufacturer: Intersil

Specifications of HSP50216KIZ

• Function: Downconverter
• Rf Type: W-CDMA
• Package / Case: 196-BGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

CIC Filter
Next, the signal is filtered by a cascaded integrator/comb
(CIC) filter. A CIC filter is an efficient architecture for
decimation filtering. The power or magnitude squared
frequency response of the CIC filter is given by:
where
The passband frequency response for 1
(N=5) order CIC filters is plotted in Figure 8. The frequency
axis is normalized to f
sample rate. Figure 10 shows the frequency response for a
5
times the CIC output sample rate) to show alias rejection for
the out of band signals. Figure 9 uses information from
Figure 10 to provide the amplitude of the first (strongest)
alias as a function of the signal frequency or bandwidth from
DC. For example, with a 5
(signal frequency is 1/8 the CIC output rate) Figure 9 shows
a first alias level of about -87dB. Figure 9 is also listed in
table form in Table 47.
P f ( )
th
and R = Decimation factor.
order filter but extends the frequency axis to f
=
M = Number of delays (1 for the HSP50216)
⎛
⎜
⎜
⎜
⎝
N = Number of stages
----------------------- -
sin
sin
(
πMf
⎛ ⎞
⎝ ⎠
πf
---- -
R
)
⎞
⎟
⎟
⎟
⎠
2N
S
/R, making f
th
order CIC and f
10
S
/R = 1 the CIC output
st
(N = 1) though 5
S
/R = 0.125
S
/R = 3 (3
HSP50216
th
The CIC filter order is programmable from 0 to 5. The
minimum decimation is 4. If the order is set to 0, there must
be at least 4 clocks between samples or the decimation
counter must be set to 4 to chose every 4th sample.
The integrator bit widths are 69, 62, 53, 44, and 34 for the 1
through 5
are all 32. The integrators are sized for decimation factors of
up to 512 with 5 stages, 2048 with 4 stages, 32768 with 3
stages, and 65536 with 1 or 2 stages. Higher decimations in
the CIC should be avoided as they will cause integrator
overflow. In the HSP50216, the integrators are slightly
oversized to reduce the quantization noise at each stage.
th
stages, respectively, while the comb bit widths
August 17, 2007
FN4557.6
st