dsphdl.CICDecimator

Decimate signal using CIC filter

Since R2019b

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Description

Thedsphdl.CICDecimatorSystem object™ decimates an input signal by using a cascaded integrator-comb (CIC) decimation filter. CIC filters are a class of linear phase finite impulse response (FIR) filters consisting of a comb part and an integrator part. The CIC decimation filter structure consists ofNsections of cascaded integrators, a rate change factor ofR, andNsections of cascaded comb filters. For more information about CIC decimation filters, seeAlgorithms.

The System object supports these combinations of input and output data.

Scalar input and scalar output — Support for fixed and variable decimation rates
Vector input and scalar output — Support for fixed decimation rates only
Vector input and vector output — Support for fixed decimation rates only

The System object provides an architecture suitable for HDL code generation and hardware deployment.

The System object supports real and complex fixed-point inputs.

To filter input data with an HDL-optimized CIC decimation filter, follow these steps:

Create thedsphdl.CICDecimatorobject and set its properties.
Call the object with arguments, as if it were a function.

To learn more about how System objects work, seeWhat Are System Objects?

Creation

Syntax

cicDecFilt = dsphdl.CICDecimator

cicDecFilt = dsphdl.CICDecimator(Name,Value)

Description

cicDecFilt= dsphdl.CICDecimatorcreates an HDL-optimized CIC decimation filter System object,cicDecFilt,默认的ties.

example

cicDecFilt= dsphdl.CICDecimator(Name,Value)creates the filter with properties set using one or more name-value arguments. Enclose each property name in single quotes.

Properties

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Unless otherwise indicated, properties arenontunable, which means you cannot change their values after calling the object. Objects lock when you call them, and thereleasefunction unlocks them.

If a property istunable, you can change its value at any time.

For more information on changing property values, seeSystem Design in MATLAB Using System Objects.

`DecimationSource`—Source of decimation factor
`'Property'`(default) |`'Input port'`

Specify whether the System object operates with a fixed or variable decimation rate.

'Property'— Use a fixed decimation rate specified by theDecimationFactorproperty.
'Input port'— Use a variable decimation rate specified by theRinput argument.

For vector inputs, the System object does not support a variable decimation rate.

`DecimationFactor`—Decimation factor
`2`(default) |integer from 1 to 2048

Specify the decimation factor as an integer from 1 to 2048. This value gives the rate at which the System object decimates the input.

Dependencies

To enable this property, set theDecimationSourceproperty to'Property'.

`MaxDecimationFactor`—Upper bound of variable decimation factor
`2`(default) |integer from 1 to 2048

Specify the upper bound of the range of valid values for theR输入参数为一个从1到2048的整数。

Note

For vector inputs, the System object does not support variable decimation.

Dependencies

To enable this property, set theDecimationSourceproperty to'Input port'.

`DifferentialDelay`—Differential delay
`1`(default) |`2`

Specify the differential delay of the comb part of the filter as either1or2cycles.

`NumSections`—Number of integrator or comb sections
`2`(default) |`1`|`3`|`4`|`5`|`6`

Specify the number of sections in either the integrator or the comb part of the System object.

`GainCorrection`—Output gain compensation
`false`(default) |`true`

Set this property totrueto compensate for the output gain of the filter.

The latency of the System object varies depending on the type of input, the decimation you specify, the number of sections, and the value of this property. For more information on the latency of the System object, seeLatency.

`OutputDataType`—Data type of output
`'Full precision'`(default) |`'Same word length as input'`|`'Minimum section word lengths'`

Choose the data type of the filtered output data.

'Full precision'— The output data type has a word length equal to the input word length plus gain bits.
'Same word length as input'— The output data type has a word length equal to the input word length.
'Minimum section word lengths'— The output data type uses the word length you specify in theOutputWordLengthproperty. When you choose this option, the System object applies a pruning algorithm internally. For more information about pruning, seeOutput Data Type.

`OutputWordLength`—Word length of output
`16`(default) |integer from 2 to 104

Word length of the output, specified as an integer from 2 to 104.

Note

When this value is2,3,4,5, or6, the System object can overflow the output data.

Dependencies

To enable this property, set theOutputDataTypeproperty to'Minimum section word lengths'.

`ResetInputPort`—Reset argument
`false`(default) |`true`

When you set this property totrue, the System object expects aresetinput argument.

Usage

Syntax

[dataOut,validOut] = cicDecFilt(dataIn,validIn)

[dataOut,validOut] = cicDecFilt(dataIn,validIn,R)

[dataOut,validOut] = cicDecFilt(dataIn,validIn,reset)

[dataOut,validOut] = cicDecFilt(dataIn,validIn,R,reset)

Description

[dataOut,validOut] = cicDecFilt(dataIn,validIn)filters and decimates the input data using a fixed decimation factor only whenvalidInistrue.

[dataOut,validOut] = cicDecFilt(dataIn,validIn,R)filters the input data using the specified variable decimation factorR. TheDecimationSourceproperty must be set to'Input port'.

[dataOut,validOut] = cicDecFilt(dataIn,validIn,reset)filters the input data whenresetisfalseand clears filter internal states whenresetistrue. The System object expects theresetargument only when you set theResetInputPortproperty totrue.

[dataOut,validOut] = cicDecFilt(dataIn,validIn,R,reset)filters the input data whenresetisfalseand clears filter internal states whenresetistrue. The System object expects theresetargument only when you set theResetInputPortproperty totrue. TheDecimationSourceproperty must be set to'Input port'.

Input Arguments

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`dataIn`—Input data
scalar|column vector

Specify input data as a scalar or a column vector with a length from 1 to 64. The input data must be a signed integer or signed fixed point with a word length less than or equal to 32. TheDecimationFactorproperty must be an integer multiple of the input frame size.

Data Types:int8|int16|int32|fi
Complex Number Support:Yes

`validIn`—Indicates valid input data
scalar

Control signal that indicates if the input data is valid. WhenvalidInis1(true), the object captures the values from thedataInargument. WhenvalidInis0(false), the object ignores the values from thedataInargument.

Data Types:logical

`R`—Variable decimation rate
scalar

Specify the decimation rate.

TheRvalue must have the data typefi(0,12,0)它必须是一个整数的范围从1到theMaxDecimationFactorproperty value.

Dependencies

To enable this argument, set theDecimationSourceproperty to'Input port'.

Data Types:fi(0,12,0)

`reset`—Clears internal states
logical scalar

Control signal that clears internal states. Whenresetis1(true), the object stops the current calculation and clears internal states. When theresetis0(false) and the inputvalidis1(true), the object captures data for processing.

For more reset considerations, see theReset Signalsection on theHardware Control Signalspage.

Dependencies

To enable this argument, set theResetInputPortproperty totrue.

Data Types:logical

Output Arguments

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`dataOut`— CIC-decimated output data
scalar | column vector

CIC-decimated output data, returned as a scalar or a column vector with a length from 1 to 64.

TheOutputDataTypeproperty sets the data type of this argument. SeeOutput Data Type.

Data Types:int8|int16|int32|fi
Complex Number Support:Yes

`validOut`— Indicates valid output data
scalar

Control signal that indicates if the output data is valid. WhenvalidOutis1(true), the object returns valid data from thedataOutargument. WhenvalidOutis0(false), values from thedataOutargument are not valid.

Data Types:logical

Object Functions

To use an object function, specify the System object as the first input argument. For example, to release system resources of a System object namedobj, use this syntax:

release(obj)

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Specific to`dsphdl.CICDecimator`

getLatency Latency of CIC decimation filter

Common to All System Objects

`step`	RunSystem objectalgorithm
`release`	Release resources and allow changes toSystem objectproperty values and input characteristics
`reset`	Reset internal states ofSystem object

Examples

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Create CIC Decimation Filter for HDL Code Generation

Open Script

This example shows how to use adsphdl.CICDecimatorSystem object™ to filter and downsample data. This object supports scalar and vector inputs. In this example, two functions are provided to work with scalar and vector inputs separately. You can generate HDL code from these functions.

Generate Frames of Random Input Samples

Set up workspace variables for the object to use. The object supports fixed and variable decimation rates for scalar inputs and only a fixed decimation rate for vector inputs. The example runs theHDLCIC_maxR8function when you set the scalar variable totrueand runs theHDLCIC_vecfunction when you set the scalar variable tofalse. For scalar inputs, choose a range of the inputvarRValuevalues and set the decimation factor valueRto the maximum expected decimation factor. For vector inputs, the input data must be a column vector of size 1 to 64 andRmust be an integer multiple of the input frame size.

R = 8;% decimation factorM = 1;% differential delayN = 3;% number of sectionsscalar = true;% true for scalar; false for vectorifscalar varRValue = [2, 4, 5, 6, 7, 8]; vecSize = 1;elsevarRValue = R;%#okfac = (factor(R)); vecSize = fac(randi(length(fac),1,1));endnumFrames = length(varRValue); dataSamples = cell(1,numFrames); varRtemp = cell(1,numFrames); framesize = zeros(1,numFrames); refOutput = []; WL = 0;% Word lengthFL = 0;% Fraction length

Generate Reference Output fromdsp.CICDecimatorSystem Object

Generate frames of random input samples and apply the samples to thedsp.CICDecimatorSystem object. Later in this example, you use the output generated by the System object as reference data for comparison. The System object does not support a variable decimation rate, so you must create and release the object for each change in decimation factor value.

totalsamples = 0;fori = 1:numFrames framesize(i) = varRValue(i)*randi([5 20],1,1); dataSamples{i} = fi(randn(vecSize,framesize(i)),1,16,8); ref_cic = dsp.CICDecimator('DifferentialDelay',M,...'NumSections',N,...'DecimationFactor',varRValue(i)); refOutput = [refOutput,ref_cic(dataSamples{i}(:)).'];%#okrelease(ref_cic);end

Run Function Containingdsphdl.CICDecimatorSystem Object

Set the properties of the System object to match the input data parameters and run the function for your input type. These functions operate on a stream of data samples rather than a frame. You can generate HDL code from these functions.

The example uses theHDLCIC_maxR8function for a scalar input.

function[dataOut,validOut] = HDLCIC_maxR8(dataIn,validIn,R)%HDLCIC_maxR8% Performs CIC decimation with an input decimation factor up to 8.% dataIn is a scalar fixed-point value.% validIn is a logical scalar value.persistentcic8;ifisempty(cic8) cic8 = dsphdl.CICDecimator('DecimationSource','Input port',...'MaxDecimationFactor',8,...'DifferentialDelay',1,...'NumSections',3);end[dataOut,validOut] = cic8(dataIn,validIn,R);end

The example uses theHDLCIC_vecfunction for a vector input.

function[dataOut,validOut] = HDLCIC_vec(dataIn,validIn)%HDLCIC_vec% Performs CIC decimation with an input vector.% dataIn is a fixed-point vector.% validIn is a logical scalar value.persistentcicVec;ifisempty(cicVec) cicVec = dsphdl.CICDecimator('DecimationSource','Property',...'DecimationFactor',8,...'DifferentialDelay',1,...'NumSections',3);end[dataOut,validOut] = cicVec(dataIn,validIn);end

To flush the remaining data, run the object by inserting the required number of idle cycles after each frame using thelatencyvariable. For more information, seeLatency.

Initialize the output to a size large enough to accommodate the output data. The final size is smaller thantotalsamplesdue to decimation.

latency = floor((vecSize - 1)*(N/vecSize)) + 1 + N + (2+(vecSize+1)*N) + 9; dataOut = zeros(1,totalsamples+numFrames*latency); validOut = zeros(1,totalsamples+numFrames*latency); idx=0;forij = 1:numFramesifscalar% scalar input with variable decimationforii = 1:length(dataSamples{ij}) idx = idx+1; [dataOut(idx),validOut(idx)] = HDLCIC_maxR8(...dataSamples{ij}(ii),...true,...fi(varRValue(ij),0,12,0));endforii = 1:latency idx = idx+1; [dataOut(idx),validOut(idx)] = HDLCIC_maxR8(...fi(0,1,16,8),...false,...fi(varRValue(ij),0,12,0));endelse% vector input with fixed decimationforii = 1:size(dataSamples{ij},2)%#okidx = idx+1; [dataOut(idx),validOut(idx)] = HDLCIC_vec(...dataSamples{ij}(:,ii),...true);endforii = 1:latency idx = idx+1; [dataOut(idx),validOut(idx)] = HDLCIC_vec(...fi(zeros(vecSize,1),1,16,8),...false);endendend

Compare Function Output with Reference Data

Compare the function results against the output from thedsp.CICDecimatorobject.

cicOutput = dataOut(validOut==1); fprintf('\nCIC Decimator\n'); difference = (abs(cicOutput-refOutput(1:length(cicOutput)))>0); fprintf(['\nTotal number of samples differed between Behavioral '...'and HDL simulation: %d \n'],sum(difference));

CIC Decimator Total number of samples differed between Behavioral and HDL simulation: 0

Explore Latency of CIC Decimator Object

Open Live Script

The latency of thedsphdl.CICDecimatorSystem object™ varies depending on how many integrator and comb sections your filter has, the input vector size, and whether you enable gain correction. Use thegetLatencyfunction to find the latency of a particular filter configuration. The latency is the number of cycles between the first valid input and the first valid output, assuming the input is continuously valid.

Create adsphdl.CICDecimatorSystem object and request the latency. The default System object filter has two integrator and comb sections, and the gain correction is disabled.

hdlcic = dsphdl.CICDecimator

hdlcic = dsphdl.CICDecimator with properties: DecimationSource: 'Property' DecimationFactor: 2 DifferentialDelay: 1 NumSections: 2 GainCorrection: false Show all properties

L_def = getLatency(hdlcic)

L_def = 5

Modify the filter object so it has three integrator and comb sections. Check the resulting change in latency.

hdlcic.NumSections = 3; L_3sec = getLatency(hdlcic)

L_3sec = 6

Enable the gain correction on the filter object with vector input size 2. Check the resulting change in latency.

hdlcic.GainCorrection = true; vecSize = 2; L_wgain = getLatency(hdlcic,vecSize)

L_wgain = 25

Algorithms

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CIC Decimation Filter

The transfer function of a CIC decimation filter is

$H (z) = {[\sum_{k = 0}^{R M - 1} z^{- k}]}^{N} = \frac{{(1 - z^{- R M})}^{N}}{{(1 - z^{- 1})}^{N}} = \frac{1}{{(1 - z^{- 1})}^{N}} \cdot \frac{{(1 - z^{- R M})}^{N}}{1} = H_{I}^{N} (z) \cdot H_{c}^{N} (z) .$

H_Iis the transfer function of the integrator part of the CIC filter.
H_Cis the transfer function of the comb part of the CIC filter.
Nis the number of sections. The number of sections in a CIC filter is defined as the number of sections in either the comb part or the integrator part of the filter. This value does not represent the total number of sections throughout the entire filter.
Ris the decimation factor.
Mis the differential delay.

CIC Filter Structure

Thedsphdl.CICDecimatorSystem object has the CIC filter structure shown in this figure. The structure consists ofNsections of cascaded integrators, a rate change factor ofR, andNsections of cascaded comb filters[1].

Designs can put the unit delay in the integrator part of the CIC filter in either the feedforward or feedback path. These two configurations yield an identical filter frequency response. However, the numerical outputs from these two configurations are different due to the latency of the paths. This System object puts the unit delay in the feedforward path of the integrator.

Fixed and Variable Decimation

The System object downsamples the integrator stage output usingR, either based on the fixed decimation rate provided using theDecimationFactorproperty or the variable decimation rate provided using theRinput argument. At the downsampler stage, the System object uses a counter to count the valid input samples, which depend on the decimation rate. Whenever the decimation rate changes, the object resets and starts a new calculation from the next sample. This mechanism prevents the System object from accumulating invalid values. Then, the System object provides the decimated output to the comb part.

Gain Correction

The gain of the System object is given by $G a i n = {(R x M)}^{N}$ .

Ris theDecimationFactorproperty value.
Mis theDifferentialDelayproperty value.
Nis theNumSectionsproperty value.

The System object implements gain correction in two parts: coarse gain and fine gain. In coarse gain correction, the System object calculates the shift value, adds the shift value to the fractional bits to create a numeric type, and then performs a bit-shift left. In fine gain correction, the System object divides the remaining gain with the coarse gain if the gain is not a power of 2 and then multiplies the coarse gain corrected value with the inverse value of fine gain. All possible shift and fine gain values are precalculated and stored in an array before the System object starts processing.

You can modify this equation as $G a i n = 2^{c G a i n} x f G a i n$ , wherecGainmeans coarse gain andfGainmeans fine gain.

$c G a i n = f l o o r (\log_{2} G a i n)$
$f G a i n = G a i n / 2^{c G a i n} = G a i n x 2^{- c G a i n}^{}$

To performGainCorrectionwhen theInterpolationSourceproperty is set to'Input port', the System object sets the output data type configured with the maximum decimation rate and bit-shifts left for all the values under the maximum decimation rate. The bit-shift value is equal to $M a x i m u m g a i n - \log_{2} (c u r r e n t g a i n)$ .

Output Data Type

This section explains how the System object determines the output data type. For example, consider a filter withDecimationFactor,DifferentialDelay, andNumSectionsvalues of 8, 1, and 3, respectively, with an input width of 16 bits.

The output word length is calculated as $B_{Out} = B_{In} + [\log_{2} (G a i n)]$ .

$G a i n = {(R x M)}^{N}$
B_Inis the input word length.
B_Outis the output word length.

When you set theOutputDataTypeproperty to'Full precision', the System object returns data with a word length of 25 bits, by adding nine gain bits to the input word length.

When you set theOutputDataTypeproperty to'Same word length as input', the object outputs data with a word length of 16, which is the same length as the input word length. The internal integrator and comb stages use the full-precision data type with 25 bits.

When you set theOutputDataTypeproperty to'Minimum section word lengths'and theOutputWordLengthproperty to16, the System object returns data with a word length of 16 bits. In this case, the object changes the bit width at each stage, based on the pruning algorithm.

If theOutputWordLengthproperty value is less than the number of bits requested at the output, the least significant bits (LSBs) at the earlier stages are pruned. The Hogenauer algorithm provides the number of LSBs to discard at each stage. This algorithm minimizes the loss of information in the output data[1].

Latency

The latency of the System object varies depending on the type of input, the decimation you specify, the number of sections, and the value of theGainCorrectionproperty. This table shows the latency of the System object.Nis the number of sections andvecLenis the length of the vector.

Input Data	Output Data	Decimation Type	Gain Correction	Latency in Clock Cycles
Scalar	Scalar	Fixed	`off`	3 +N. WhenR= 1, 2 +N.
Scalar	Scalar	Fixed	`on`	3 +N+ 9. WhenR= 1, 2 +N+ 9.
Scalar	Scalar	Variable	`off`	4 +N. WhenR_max= 1, 3 +N.
Scalar	Scalar	Variable	`on`	4 +N+ 9. WhenR_max= 1, 3 +N+ 9.
Vector	Scalar	Fixed	`off`	`floor`((vecLen– 1) x (N/vecLen)) + 1 +N+ (2 + (vecLen+ 1) xN
Vector	Scalar	Fixed	`on`	`floor`((vecLen– 1) x (N/vecLen)) + 1 +N+ (2 + (vecLen+ 1) xN) + 9
Vector	Vector	Fixed	`off`	`floor`((vecLen– 1) x (N/vecLen)) + 1 +N+ (2 + (vecLen+ 1) xN
Vector	Vector	Fixed	`on`	`floor`((vecLen– 1) x (N/vecLen)) + 1 +N+ (2 + (vecLen+ 1) xN) + 9

Note

For vector inputs, the System object does not support variable decimation.

Scalar Input

This section shows the output of the System object for a scalar input with differentR,M, andNvalues.

This figure shows the output of the System object with the default configuration, that is, with a fixed decimation rate andDecimationFactor,DifferentialDelay, andNumSectionsvalues of 2, 1, and 2, respectively. The System object returns valid output data at every second cycle based on the fixedDecimationFactorvalue of 2. The latency of the System object is 5 clock cycles, calculated as 3 +N.

The output of the System object shows the latency of 5 clock cycles.

This figure shows the output of the System object with a fixed decimation rate,DecimationFactor,DifferentialDelay, andNumSectionsvalues of 8, 1, and 3, respectively, andGainCorrectionset totrue. The System object returns valid output data at every eighth cycle based on the fixedDecimationFactorvalue of 8. The latency of the object is 15 clock cycles and is calculated as 3 +N+ 9.

The output of the System object shows the latency of 15 clock cycles.

This figure shows the output of the System object for variableRvalues of 2, 4, and 8 along withMandNvalues of 1 and 3. TheGainCorrectionproperty is set tofalse. The System object returns valid output data at the second, fourth, and eighth cycles corresponding to theRvalues 2, 4, and 8, respectively. The System object acceptsRargument value changes only when the inputvalidInis1(true). The latency of the System object is 7 clock cycles, calculated as 4 +N.

The output of the System object shows the latency of 7 clock cycles.

Vector Input

This section shows the output of the System object for a vector input with differentR,M, andNvalues.

This figure shows the output of the System object for a two-element column vector input with the default configuration, that is, with a fixed decimation rate andDecimationFactor,DifferentialDelay, andNumSectionsvalues of 2, 1, and 2, respectively. The latency of the object is 12 clock cycles.

The output of the System object shows the latency of 12 clock cycles.

This figure shows the output of the System object for an eight-element column vector input with a fixed decimation rate,R,M, andNvalues of 8, 1, and 3, respectively, andGainCorrectionset totrue. The latency of the object is 44 clock cycles.

The output of the System object shows the latency of 44 clock cycles.

Performance

The performance of the synthesized HDL code varies with your target and synthesis options. It also varies based on the input data type.

This table shows the resource and performance data synthesis results of the object for a scalar input of typefixdt(1,16,0)with fixed and variable decimation rates and for a two-element column vector input with fixed decimation rateDecimationFactor,DifferentialDelay, andNumSections值是2,1和2分别。生成d HDL is targeted to the Xilinx^®Zynq^®-7000 ZC706 Evaluation Board.

Input Data	Decimation Type	Slice LUTs	Slice Registers	Maximum Frequency in MHz
Scalar	Fixed rate	101	166	711.74
Scalar	Variable rate	206	186	441.70
Vector	Fixed rate	218	627	624.61

The resources and frequencies vary based on the type of input data and the values ofR,M, andN,以及其他属性。使用一个向量input can increase the throughput, however, doing so also increases the number of hardware resources that the System object uses.

References

[1] Hogenauer, E. “An Economical Class of Digital Filters for Decimation and Interpolation.”IEEE Transactions on Acoustics, Speech, and Signal Processing29, no. 2 (April 1981): 155–62. https://doi.org/10.1109/TASSP.1981.1163535.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

This System object supports C/C++ code generation for accelerating MATLAB^®simulations, and for DPI component generation.

HDL Code Generation
Generate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.

The software supportsdoubleandsingledata types for simulation, but not for HDL code generation.

To generate HDL code from predefined System objects, seeHDL Code Generation from Viterbi Decoder System Object(HDL Coder).

Version History

Introduced in R2019b

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R2022a:Moved toDSP HDL ToolboxfromDSP System Toolbox

Before R2022a, this System object was nameddsp.HDLCICDecimationand was included in the DSP System Toolbox™.

R2022a:Changes to decimation factor arguments

You can now set the decimation factor to1. In previous releases, a decimation factor of1was invalid.
ResetInproperty is renamed toResetInputPort.

Configuration	Before R2022a	After 2022a
Variable decimation factor	Select the`VariableDownsample`property and set the`DecimationFactor`parameter to the maximum expected decimation factor.	Set the`DecimationSource`property to`Input port`and set the`MaxDecimationFactor`property to the maximum expected decimation factor. The`decimFactor`port is renamed to`R`.
Fixed decimation factor	Clear the`VariableDownsample`property and set the`DecimationFactor`property to the desired decimation factor.	Set the`DecimationSource`property to`Property`and set the`DecimationFactor`property to the desired decimation factor.

R2021b:High-throughput interface

The object accepts and returns a column vector of elements that represent samples in time. The input vector can contain up to 64 samples. When you use frame-based input, you must use a fixed decimation factor.

R2020a:Gain correction and programmable decimation factor

You can optionally enable automatic gain correction. You can also specify the decimation factor as an input argument.

dsphdl.CICDecimator

Description

Creation

Syntax

Description

Properties

DecimationSource—Source of decimation factor'Property'(default) |'Input port'

DecimationFactor—Decimation factor2(default) |integer from 1 to 2048

Dependencies

MaxDecimationFactor—Upper bound of variable decimation factor2(default) |integer from 1 to 2048

Dependencies

DifferentialDelay—Differential delay1(default) |2

NumSections—Number of integrator or comb sections2(default) |1|3|4|5|6

GainCorrection—Output gain compensationfalse(default) |true

OutputDataType—Data type of output'Full precision'(default) |'Same word length as input'|'Minimum section word lengths'

OutputWordLength—Word length of output16(default) |integer from 2 to 104

Dependencies

ResetInputPort—Reset argumentfalse(default) |true

Usage

Syntax

Description

Input Arguments

dataIn—Input datascalar|column vector

validIn—Indicates valid input datascalar

R—Variable decimation ratescalar

Dependencies

reset—Clears internal stateslogical scalar

Dependencies

Output Arguments

dataOut— CIC-decimated output datascalar | column vector

validOut— Indicates valid output datascalar

Object Functions

Specific todsphdl.CICDecimator

Common to All System Objects

Examples

Create CIC Decimation Filter for HDL Code Generation

Explore Latency of CIC Decimator Object

Algorithms

CIC Decimation Filter

CIC Filter Structure

Fixed and Variable Decimation

Gain Correction

Output Data Type

Latency

Performance

References

Extended Capabilities

C/C++ Code GenerationGenerate C and C++ code using MATLAB® Coder™.

HDL Code GenerationGenerate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.

Version History

R2022a:Moved toDSP HDL ToolboxfromDSP System Toolbox

R2022a:Changes to decimation factor arguments

R2021b:High-throughput interface

R2020a:Gain correction and programmable decimation factor

See Also

Objects

Blocks

`DecimationSource`—Source of decimation factor
`'Property'`(default) |`'Input port'`

`DecimationFactor`—Decimation factor
`2`(default) |integer from 1 to 2048

`MaxDecimationFactor`—Upper bound of variable decimation factor
`2`(default) |integer from 1 to 2048

`DifferentialDelay`—Differential delay
`1`(default) |`2`

`NumSections`—Number of integrator or comb sections
`2`(default) |`1`|`3`|`4`|`5`|`6`

`GainCorrection`—Output gain compensation
`false`(default) |`true`

`OutputDataType`—Data type of output
`'Full precision'`(default) |`'Same word length as input'`|`'Minimum section word lengths'`

`OutputWordLength`—Word length of output
`16`(default) |integer from 2 to 104

`ResetInputPort`—Reset argument
`false`(default) |`true`

`dataIn`—Input data
scalar|column vector

`validIn`—Indicates valid input data
scalar

`R`—Variable decimation rate
scalar

`reset`—Clears internal states
logical scalar

`dataOut`— CIC-decimated output data
scalar | column vector

`validOut`— Indicates valid output data
scalar

Specific to`dsphdl.CICDecimator`

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

HDL Code Generation
Generate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.