IPR-CIC Altera, IPR-CIC Datasheet - Page 25

• Manufacturer Part Number: IPR-CIC
• Description: IP CORE Renewal Of IP-CIC
• Manufacturer: Altera

Specifications of IPR-CIC

• Software Application: IP CORE, DSP Filters And Transforms
• Supported Families: Arria GX, Cyclone, HardCopy, Stratix, Stratix II
• Core Architecture: FPGA
• Core Sub-architecture: Arria, Cyclone, Stratix
• Rohs Compliant: NA
• Lead Free Status / RoHS Status: na

Cascaded Integrator Comb Filters
© December 2010 Altera Corporation
:
Cascaded Integrator Comb (CIC) filters are widely used in modern communication
systems. Using CIC filters provides a silicon efficient architecture for performing
sample rate conversion. This is achieved by extracting baseband signals from narrow-
band sources using decimation, and constructing narrow-band signals from
processed baseband signals using interpolation. The key advantage of CIC filters is
that they use only adders and registers, and do not require multipliers to implement
in hardware for handling large rate changes.
A CIC filter (also known as a Hogenauer filter) can be used to perform either
decimation or interpolation. A decimation CIC filter comprises a cascade of
integrators (called the integrator section), followed by a down sampling block
(decimator) and a cascade of differentiators (called the differentiator or comb section).
Similarly an interpolation CIC filter comprises a cascade of differentiators, followed
by an up sampling block (interpolator) and a cascade of integrators.
In a CIC filter, both the integrator and comb sections have the same number of
integrators and differentiators. Each pairing of integrator and differentiator is called a
stage. The number of stages (N) has a direct effect on the frequency response of a CIC
filter. The response of the filter is determined by configuring the number of stages N,
the rate change factor R and the number of delays in the differentiators (called the
differential delay) M. In practice, the differential delay is set to 1 or 2.
Figure 4–1
Figure 4–1. Integrator
Figure 4–2
Figure 4–2. Differentiator
shows an integrator.
shows a differentiator.
+
z
-M
4. Functional Description
z
z
-1
-1
+
-
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CIC MegaCore Function User Guide