Fixed-Point Filters

R2026b

Fixed-point filter design

You can model fixed-point signal processing filtering algorithms and analyze the effects of quantization on system behavior and performance using the DSP System Toolbox™ and Fixed-Point Designer™ functionality. For a list of DSP System Toolbox System objects that support fixed-point operations, see System Objects in DSP System Toolbox that Support Fixed-Point Design. For a list of DSP System Toolbox blocks that support fixed-point operations, use the showsignalblockdatatypetable function.

Objects

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Single-Rate Filters

`dsp.AllpoleFilter`	IIR Filter with no zeros
`dsp.Differentiator`	Direct form FIR fullband differentiator filter
`dsp.FIRFilter`	Static or time-varying FIR filter
`dsp.HighpassFilter`	FIR or IIR highpass filter
`dsp.IIRFilter`	Infinite impulse response (IIR) filter
`dsp.LowpassFilter`	FIR or IIR lowpass filter
`dsp.SOSFilter`	Implement cascade of second order section filters

Multirate and Multistage Filters

`dsp.CICCompensationDecimator`	Compensate for CIC decimation filter using FIR decimator
`dsp.CICCompensationInterpolator`	Compensate for CIC interpolation filter using FIR interpolator
`dsp.CICDecimator`	Decimate signal using cascaded integrator-comb (CIC) filter
`dsp.CICInterpolator`	Interpolate signal using cascaded integrator-comb filter
`dsp.DDC`	Digital downconverter (Since R2026b)
`dsp.DUC`	Digital upconverter (Since R2026b)
`dsp.DigitalDownConverter`	Translate digital signal from intermediate frequency (IF) band to baseband and decimate it
`dsp.DigitalUpConverter`	Interpolate digital signal and translate it from baseband to IF band
`dsp.FarrowRateConverter`	Polynomial sample rate converter with arbitrary conversion factor
`dsp.FIRDecimator`	Perform polyphase FIR decimation
`dsp.FIRHalfbandDecimator`	Decimate signal using polyphase FIR halfband filter
`dsp.FIRHalfbandInterpolator`	Interpolate signal using polyphase FIR halfband filter
`dsp.FIRInterpolator`	Perform polyphase FIR interpolation
`dsp.FIRRateConverter`	Perform polyphase FIR sample rate conversion
`dsp.SubbandAnalysisFilter`	Decompose signal into high-frequency and low-frequency subbands
`dsp.SubbandSynthesisFilter`	Reconstruct signal from high-frequency and low-frequency subbands

Adaptive Filters

dsp.LMSFilter Compute output, error, and weights of least mean squares (LMS) adaptive filter

Functions

`freqrespest`	Frequency response estimate via filtering
`freqrespopts`	Create an options object for frequency response estimate
`freqz`	Frequency response of discrete-time filter System object
`impz`	Impulse response of discrete-time filter System object
`isstable`	Verify that discrete-time filter System object is stable
`noisepsd`	Power spectral density of filter output due to round-off noise
`noisepsdopts`	Create an options object for output noise PSD computation
`reorder`	Reorder second-order sections of biquadratic filter System object
`scale`	Scale second-order sections
`specifyall`	Fully specify fixed-point filter System object settings
`zplane`	Z-plane zero-pole plot for discrete-time filter System object

Blocks

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Single-Rate Filters

	Allpole Filter	Model allpole filters
	Biquad Filter	(To be removed) Model biquadratic IIR (SOS) filters
	Differentiator Filter	Direct form FIR fullband differentiator filter
	Discrete Filter	Model Infinite Impulse Response (IIR) filters
	Discrete FIR Filter	Model FIR filters
	Highpass Filter	Design FIR or IIR highpass filter
	Lowpass Filter	Design FIR or IIR lowpass filter

Multirate and Multistage Filters

	CIC Compensation Decimator	Compensate for CIC filter using FIR decimator
	CIC Compensation Interpolator	Compensate for CIC filter using FIR interpolator
	CIC Decimation	Decimate signal using cascaded integrator-comb filter
	CIC Interpolation	Interpolate signal using cascaded integrator-comb filter
	Digital Down-Converter	Translate digital signal from intermediate frequency (IF) band to baseband and decimate it
	Digital Up-Converter	Interpolate and translate digital signal from baseband to intermediate frequency (IF) band
	Farrow Rate Converter	Polynomial sample-rate converter with arbitrary conversion factor
	FIR Decimation	Perform polyphase FIR decimation
	FIR Halfband Decimator	Decimate signal using polyphase FIR halfband filter
	FIR Halfband Interpolator	Interpolate signal using polyphase FIR halfband filter
	FIR Interpolation	Perform polyphase FIR interpolation
	FIR Rate Conversion	Perform polyphase FIR sample rate conversion
	Two-Channel Analysis Subband Filter	Decompose signal into high-frequency and low-frequency subbands
	Two-Channel Analysis Subband Filter	Decompose signal into high-frequency and low-frequency subbands

Adaptive Filters

LMS Filter

Compute output, error, and weights using least mean squares (LMS) adaptive algorithm

Topics

Fixed-Point Precision Rules for Avoiding Overflow in FIR Filters
Precision Rules for Avoiding Overflow in FIR Filters.
Create an FIR Filter Using Integer Coefficients
Learn how to create an FIR filter using integer coefficients.
Fixed-Point Filter Design in MATLAB
Design filters for use with fixed-point input.

Featured Examples

Sigma-Delta A/D Conversion

Model analog-to-digital conversion by implementing a sigma-delta algorithm.

Open Script

Cochlear Implant Speech Processor

Simulate the design of a cochlear implant that can be placed in the inner ear of a profoundly deaf person to restore partial hearing. Signal processing is used in cochlear implant development to convert sound to electrical pulses. The pulses can bypass the damaged parts of a deaf person's ear and be transmitted to the brain to provide partial hearing.

Open Model

Design and Analysis of a Digital Down Converter

Use the digital down converter (DDC) System object™ to emulate the TI Graychip 4016 digital down converter in a simple manner. We base the example on a comparison with the GSM Digital Down Converter example. We show how the DDC System object can be used to design and analyze the decimation filters and to quickly explore different design options that meet various passband and stopband frequency and attenuation specifications. This example requires a Fixed-Point Designer™ license.

Open Live Script