Nonrecursive digital filters have a weighting sequence impulse response, git, which is finite in length, and consequently this type of filter is commonly referred to as a finite impulse response fir filter. Characterization, description, testing, recursive and non recursive fir and iir, discrete fourier transform, z transform, discrete time systems, frequency domain, simple digital filters, continuous time signals, analog filter design, digital filter structure. Each one of the designed decimators shows better stopband attenuation for a given order and decimation factor than the cic or recently. In this section we propose a new architecture for non recursive cic filters with integer multiple pxtors. In this study, the authors advances three new cascaded decimator structures with integer coefficients designed using a polynomial factorisation approach. In many applications, a cic based decimator is followed by a secondary decimation stage. To find the solution of this problem, first we will define the filter characteristics to find the respective. The term nonrecursive intrinsically means that the output of the filter, ynt, is computed using the present input, xnt, and previous inputs, xn. This filter worked with sampling frequency of 5 mhz. In this paper author presents an optimized design of nonrecursive cic filter structure12. Nth order cascade integrated comb filter take n moving average filters in sequence with decimation at the end rearrange all integrators first, and comb filters. Dutta roy gives 43 video lectures on digital signal processing.
Recursive digital filter design the subject of digital filter design is enormousmuch larger than we can hope to address in this book. I faster response to the input signal, i and shorter frequency response transition width. An improved recursive and nonrecursive comb filter for. A beginners guide to cascaded integratorcomb cic filters. However, the disadvantage of a cic filter is that its pass band is not flat, which is undesirable in many applications. In this section we propose a new architecture for nonrecursive cic filters with integer multiple pxtors. Poly phase decomposition was utilized for the realization of the first section in a non recursive form whereas the second section was realized in a recursive. Additionally, the magnitude response of the cic filter has a high droop in the desired passband and low stopband attenuation. The cascaded integratorcomb cic filter is a class of hardwareefficient. Recursive digital lters are often known as i in nite impulse response iir filters. Cic filter is a preferred technique for this purpose. Results and comparisions the different cic filter structures are designed in matlab simulink environment.
This cascadedfilter architecture has valuable benefits reduced complexity and reduced power consumption in hardware but the crucial benefit of using cic filters is that they require no multiplication. In order to resolve this problem the nonrecursive structure of eq. The implementation results show that nonrecursive comb filter. Rate change 100 number of stages 4 differential delay 1 id like to calculate the group delay of this filter but i am not sure how. Poly phase decomposition was utilized for the realization of the first section in a nonrecursive form whereas the. Understanding cascaded integratorcomb filters cic and. Cic filter has low attenuation and a droop in the desired passband that is dependent upon the decimation factor r and the number n of section in cascade. Vlsi implementation of cascaded integrator comb filters. The second trick shows a way to eliminate the integrators from cic. Design guidelines are provided with the aim to simplify the design of the constituent decimation. Abed proposed a decimation filter which uses a cascade of nonrecursive cic, iir and halfband fir filters 20. The design of fir non recursive and iir recursive filters were made following the design specifications for this application.
Design and implementation of efficient cic filter structure. Comparison of classical cic and a new class of stopbandimproved cic filters 63 where n is an integer parameter, and filter order is equal to n1. Applying third identity, the factor of m down sampler is moved and placed behind the integrator section and before the comb section as shown in figure 5. The transfer function of the resulting decimation filter, also known as a rrs recursive running sum or comb filter is given by. Ddc the decimation filter can be done poly phase and cic based ddc can be implemented in wireless communication systems. The authors in 9 worked on realizing an efficientmultistage comb rotated sinc rs decimator filter with the use of recursive and nonrecursive architectures. Vlsi implementation of cascaded integrator comb filters for.
The novel filter functions are given in recursive and non recursive forms, suitable for software and hardware realizations, respectively. In this paper, modified cic fir filter functions which preserve the cic filter simplicity avoiding the multipliers, are designed. Enhancement of the performance characteristics of cic. Because their frequency magnitude responses are sinxxlike, cic filters are typically followed, or preceded, by linearphase lowpass tappeddelay line finite impulse response fir filters whose tasks are to compensate for the cic filters nonflat passband. Digital filter analog filter recursive filter a 0 0. Nonrecursive cascaded integratorcomb decimation filters. In 1981, eugene hogenauer 3 invented a new class of economical digital filter for decimation called a cascaded integrator comb filter cic or recursive comb filter. Hamming, sharpening the response of a symmetric nonrecursive filter by multiple use of the same filter, ieee trans. Polyphase implementation structure of cic filter 4. In 1981, eugene hogenauer 2 invented a new class of economical digital filter for decimation called a cascaded integrator comb filter cic or recursive comb filter. Implementation of cic filter for multirate transmission systems dr.
They execute very rapidly, but have less performance and flexibility than other digital filters. However, for convenience, the term fir filter will be taken to mean a nonrecursive filter in this book. Iir fir implementation structure of cic filter fig. It should be pointed out at this stage that it is possible to design some fir filters which are recursive. Abed proposed a decimation filter which uses a cascade of non recursive cic, iir and halfband fir filters 20. Fortunately, this problem can be alleviated by a compensation filter. More details on a comparison of the performances of the recursive and nonrecursive implementations are given in 2. Example of cascaded integrator comb filter in matlab.
It does not require any multiplier circuit and also uses recursive or nonrecursive filter4. Master theses cic filter design with hls webthesis politecnico di. The cic filter is based upon a lowpass filtration system. Pdf an improved recursive and nonrecursive comb filter for. Cic decimation filter block diagram above f igure 4 shows the cic decimation filter block diagram. Pavlovic university of nis, faculty of electronic engineering, nis, serbia abstract. However, the filter exhibits a high passband droop and a low attenuation in so called folding bands bands around the zeros of cic filter, which can be not. Nonrecursive digital filters are often known as finite impulse response fir filters as a nonrecursive digital filter has a finite number of coefficients in the impulse response hn. Let me briefly share my understanding on the cascaded integrator comb cic filter, thanks to the nice article. The cic filter has the following transfer function. Design and implementation of efficient cic filter structure for decimation. Nonrecursive decimation filters with arbitrary integer. Design of five stage cic decimation filter for signal processing. In digital signal processing, a cascaded integratorcomb cic is an optimized class of finite impulse response fir filter combined with an interpolator or decimator a cic filter consists of one or more integrator and comb filter pairs.
Application of hardware efficient cic compensation filter in. Design of five stage cic decimation filter for signal. Cic filter design the antialiasing filter is the important role of decimation filter and also used to find out the less number of decimation stages that could provide useful implementation about cic filter. The impulse response, the filters response to a kronecker delta input, is finite because it settles to zero in a finite number of sample intervals. Hence the output of the frontend cic decimator is not at the nyquist rate. Infinite impulse response an overview sciencedirect topics. This feedback typically results in an unending impulse response commonly referred to as infinite impulse response iir, characterised by either exponentially growing, decaying, or sinusoidal signal output components however, a recursive filter does not always have an infinite. Comparison of classical cic and a new class of stopbandimproved cic filters formed by cascading nonidentical comb sections dejan n. Vlsi design of a high performance decimation filter used for digital filtering. Implementation of cic filter for multirate transmission systems. In the case of a decimating cic, the input signal is fed through one or more cascaded integrators, then a downsampler, followed by one or more comb. Digital filters perform the operations of addition, subtraction, multiplication, and division on sampled data. The design of fir nonrecursive and iir recursive filters were made following the design specifications for this application. Recursive digital filters recursive digital lters are often known as i in nite impulse response iir filters as the impulse response of an iir lter often has an in nite number of coe cients.
Cascaded integrator comb cic filters are in wide use in oversampled analogtodigital converters. These are known as cascaded integrator comb filterscic filters because their. Fir filter sharpening by frequency masking and pipelininginterleaving technique the designs are a diverse set of dsp functions of varying complexity which includes recursive and nonrecursive filter structures. The use of nonrecursive filter structures has been increasing in the recent years for various applications. Application of hardware efficient cic compensation filter. Jul 01, 2007 as you may have observed, the cic filter is a recursive implementation of a moving average filter let us say of length n. A polyphase structure 9, needs maximum area and minimum power. Nonrecursive filter article about nonrecursive filter by. Hogenauer invented the cic filter structures is economical class of linear phase, fir filter.
Nonrecursive implementation structure of cic filter fig. Implementation of cic filter for multirate transmission. Typically, when interpolation by a factor i, we insert i1 zeros inbetween the samples and then do a filtering to remove the aliases. Recursive digital filter design introduction to digital filters. The transfer function of conventional cic filter is given by v 5.
Both recursive and nonrecursive architectures are discussed by focusing on a speci. An improved recursive and nonrecursive comb filter for dsp. An efficient solution for optimizing and the cic decimation filter is nonrecursive decimation filter. An enhanced version of the nonrecursive carrysaveadderbased structures for cic decimation filters for high speed functions was proposed by gao et al. The use of non recursive filter structures has been increasing in the recent years. The recursive form of a novel class of cic fir filter functions with a normalized amplitude response characteristic is l n n n n l n n n n n n n n z. Non recursive digital filters non recursive digital lters are often known as i finite impulse response fir filters as a non recursive digital lter has a nite number of coe cients in the impulse response hn.
However, a surprisingly large number of applications can be addressed using small filter sections which are easily designed by hand, as exemplified in appendix b. In order to resolve this problem the nonrecursive structure of 1 can be used 2, 3. A finite impulse response fir filter is a type of a digital filter. Selecting the parameters fo r the designing cic filter is explained below. Lets assume that the decimation factor can be factored into 2p3g5r7s11t. As shown in this example, a single pole lowpass recursive filter smoothes the edge of a step input, just as an electronic rc filter. The implementation results show that nonrecursive comb filter has capability of. The authors in 9 worked on realizing an efficientmultistage comb rotated sinc rs decimator filter with the use of recursive and non recursive architectures. However, for convenience, the term fir filter will be taken to mean a non recursive filter in this book. The comparison is made between integrator comb filter cic or recursive comb filter. A cic filter is an efficient implementation of a movingaverage filter. The cic filter block diagram is shown in figure 2 figure 2.
The structure of nonrecursive decimation filter is based upon conventional cic decimation filter 14. The novel class of cic fir filter functions is designed based on the classical cic filters, by spreading the delays in the cic filter comb stages. In this paper author presents an optimized design of non recursive cic filter structure12. A variation on an existing technique that would allow a partially non recursive and, therefore, potentially higher speed implementation is presented for cic filters with power of two decimation. In this paper we propose a new class of selective cic filters in recursive and nonrecursive form. Because their frequencymagnituderesponse envelopes are sinxxlike, cic filters are typically either followed or preceded by higher performance linearphase lowpass tappeddelayline fir filters whose tasks are to compensate for the cic filter s non flat passband. I have an interpolating cascaded integrator comb cic filter designed as so. To see this, consider how a moving average filter can be implemented recursively by adding the newest sample x n \displaystyle xn to the previous result y n. Vlsi design of a high performance decimation filter used.
The novel filter functions are given in recursive and nonrecursive forms, suitable for software and hardware realizations, respectively. Wide band rate conversion using cic filters for wireless. Non recursive digital filters have a weighting sequence impulse response, git, which is finite in length, and consequently this type of filter is commonly referred to as a finite impulse response fir filter. Because their frequency magnitude responses are sinxxlike, cic filters are typically followed, or preceded, by linearphase lowpass tappeddelay line finite impulse response fir filters whose tasks are to compensate for the cic filter s non flat passband. This can be obtained by parallel processing methods and hence the sampling rate of the cic filter is increased by this proposed structure. Nonrecursive digital filters nonrecursive digital lters are often known as i finite impulse response fir filters as a nonrecursive digital lter has a nite number of coe cients in the impulse response hn.
Sagar haramaya institute of technolog y, hu, india. Due to its simplicity, the cic filter is usually used in the first stage of decimation. When better stopband suppression is required, it is a common procedure to cascade multiple filter sections until. Among the types of digital filter are the infinite impulse response iir filter, the finite impulse response fir filter 15, and the computationally efficient cascaded integrator comb cic filter 16. Pdf power estimation of recursive and nonrecursive cic. In signal processing, a recursive filter is a type of filter which reuses one or more of its outputs as an input. Because their frequencymagnituderesponse envelopes are sinxxlike, cic filters are typically either followed or preceded by higher performance linearphase lowpass tappeddelayline fir filters whose tasks are to compensate for the cic filters nonflat passband. Cic filters are derived from the notion of a recursive runningsum filter, which is itself an efficient form of a nonrecursive moving averager. Among the types of digital filter are the infinite impulse response iir filter, the finite impulse response fir filter 15, and the computationally efficient cascaded integrator comb cic filter. Cic is the combination of equal number of integrator and comb stages. Design of nonrecursive digital filters springerlink. A variation on an existing technique that would allow a partially nonrecursive and, therefore, potentially higher speed implementation is presented for cic filters with power of two decimation. Matlab simulink, xilinx virtexv, cic filter, filter sharpening.
Here in the figure we are designing cic decimation filter with the help of simulink software in matlab. Digital recursive filters can mimic analog filters composed of resistors and capacitors. A nonrecursive filter is also known as an fir or finite impulse response filter. The five stage cic filter is proposed in this paper. The transfer function of the cic filter in zdomain is given as 1. Cic filter is equivalent to a number of rectangular windows cascaded recursive filter form, and therefore has a more significant performance limitations. The cic filter is a preferred technique for this purpose. The transfer function of the cic filter in zdomain is given in 1.
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