How does a CIC filter work?

How does a CIC filter work?

A CIC filter consists of an equal number of stages of ideal integrator filters and comb filters. Its frequency response may be tuned by selecting the appropriate number of cascaded integrator and comb filter pairs. The highly symmetric structure of a CIC filter allows efficient implementation in hardware.

What is differential delay in CIC filter?

The feedforward portion of the CIC filter is called the comb section, whose differential delay is D, while the feedback section is typically called an integrator. The comb stage subtracts a delayed input sample from the current input sample, and the integrator is simply an accumulator.

What is a CIC decimator?

The CIC Decimation block performs a sample rate decrease (decimation) on an input signal by an integer factor. Cascaded Integrator-Comb (CIC) filters are a class of linear phase FIR filters comprised of a comb part and an integrator part.

What is decimation filter?

Decimation is the process of reducing the sampling frequency of a signal to a lower sampling frequency that differs from the original frequency by an integer value. Decimation also is known as down-sampling. Decimation filters help you remove the excess bandwidth and reduce the sampling frequency of the signal.

How does a polyphase filter work?

A polyphase quadrature filter, or PQF, is a filter bank which splits an input signal into a given number N (mostly a power of 2) of equidistant sub-bands. These sub-bands are subsampled by a factor of N, so they are critically sampled.

What does a comb filter do?

In signal processing, a comb filter is a filter implemented by adding a delayed version of a signal to itself, causing constructive and destructive interference. The frequency response of a comb filter consists of a series of regularly spaced notches, giving the appearance of a comb.

How do you test a CIC filter?

Two Easy Ways To Test Multistage CIC Decimation Filters

1. The traditional method for testing such a filter implementation is to apply to the filter a low-frequency sinusoidal xin(n) input sequence of frequency fin Hz, having N samples/cycle, and a peak amplitude of Ain.
2. then the filter is operating properly.

What is FIR filter in DSP?

In signal processing, a finite impulse response (FIR) filter is a filter whose impulse response (or response to any finite length input) is of finite duration, because it settles to zero in finite time. FIR filters can be discrete-time or continuous-time, and digital or analog.

What is difference between downsampling and decimation?

Loosely speaking, “decimation” is the process of reducing the sampling rate. In practice, this usually implies lowpass-filtering a signal, then throwing away some of its samples. “Downsampling” is a more specific term which refers to just the process of throwing away samples, without the lowpass filtering operation.

What is polyphase implementation filter?

DSP: Polyphase Implementation of Filtering. A Problem With Exchanging The Order of. Up/Downsampling and Filtering. Recall our equivalent structures: We prefer (a) in both cases because the filtering is done at the lower sampling rate.

What is polyphase filter structure?

A polyphase quadrature filter, or PQF, is a filter bank which splits an input signal into a given number N (mostly a power of 2) of equidistant sub-bands. These sub-bands are subsampled by a factor of N, so they are critically sampled. This critical sampling introduces aliasing.

What do you need to know about CIC filters?

Understanding CIC Compensation Filters. Introduction The cascaded integrator-com b (CIC) filter is a class of hardware-efficient linear phase finite impulse response (FIR) digital filters. CIC filters achieve sampling rate decrease (decimation) and sampling rate increase (interpolation) without using multipliers.

What is the structure of a CIC Fi LTER?

A CIC filter consists of an equal number of stages of ideal integrator filters and comb filters. Its frequency response may be tuned by selecting the appropriate number of cascaded integrator and comb filter pairs. The highly symmetric structure of a CIC fi lter allows efficient implementation in hardware.

Which is the inverse of the CIC filter?

To overcome the magnitude droop, a FIR filter that has a magnitude response that is the inverse of the CIC filter can be applied to achieve frequency response correction. Such filters are called “compensation filters.” For data rate down conversion, the compensation filter follows the CIC filter.

How to create a CIC compensation filter in MATLAB?

Any filter design tool that generates filter coefficients based on the specified frequency response can be used to design a CIC compensation filter. In this application note, the MATLAB Signal Processing Toolbox function fir2 is used to generate the coefficients for CIC compensation filters.