09-01-2012, 09:54 AM
1 Introduction
As data converters become faster and faster, the application of narrow-band extraction from
wideband sources, and narrow-band construction of wideband signals is becoming more
important. These functions require two basic signal processing procedures: decimation and
interpolation. And while digital hardware is becoming faster, there is still the need for
ecient solutions. Techniques found in [CR83] work very well in practice, but large rate
changes require very narrow band lters. Large rate changes require fast multipliers and
very long lters. This can end up being the largest bottleneck in a DSP system.
In [Hog81], an ecient way of perfoming decimation and interpolation was introduced.
Hogenauer devised a
exible, multiplier-free lter suitable for hardware implementation, that
can also handle arbitrary and large rate changes. These are known as cascaded integratorcomb
lters, or CIC lters for short.
This paper sumarizes the ndings published in [Hog81]. An overview can also be found in
[Fre94]. An extension of CIC lters has been published in [KJW97], and is brie
y mentioned
here. When in doubt, the reader should refer to these sources.
2 Building Blocks
The two basic building blocks of a CIC lter are an integrator and a comb. An integrator is
simply a single-pole IIR lter with a unity feedback coe cient:
y[n] = y[n
As data converters become faster and faster, the application of narrow-band extraction from
wideband sources, and narrow-band construction of wideband signals is becoming more
important. These functions require two basic signal processing procedures: decimation and
interpolation. And while digital hardware is becoming faster, there is still the need for
ecient solutions. Techniques found in [CR83] work very well in practice, but large rate
changes require very narrow band lters. Large rate changes require fast multipliers and
very long lters. This can end up being the largest bottleneck in a DSP system.
In [Hog81], an ecient way of perfoming decimation and interpolation was introduced.
Hogenauer devised a
exible, multiplier-free lter suitable for hardware implementation, that
can also handle arbitrary and large rate changes. These are known as cascaded integratorcomb
lters, or CIC lters for short.
This paper sumarizes the ndings published in [Hog81]. An overview can also be found in
[Fre94]. An extension of CIC lters has been published in [KJW97], and is brie
y mentioned
here. When in doubt, the reader should refer to these sources.
2 Building Blocks
The two basic building blocks of a CIC lter are an integrator and a comb. An integrator is
simply a single-pole IIR lter with a unity feedback coe cient:
y[n] = y[n
