IIR Filter
An IIR (Infinite Impulse Response) filter is a foundation element in Digital Signal Processing (DSP). It is one of two types of digital filters used in DSP applications and is an alternative to Finite Impulse Response (FIR) filters. The response in IIRs is considered infinite since there is feedback in the filter and they may be either analog or digital. IIRs are more efficient than FIRs for narrow transition bands, but it takes more time and money to develop a new IIR filter depending on the application.
What are the Advantages of IIR Filters?
IIR filters can achieve their designed filtering characteristics by using fewer calculations and less memory than FIR filters. They outperform other filters for narrow transition bands. They also provide a better approximation for traditionally analog systems in digital applications than competing filters.
What are the Disadvantages of IIR Filters?
IIR filters have several disadvantages, which include: being harder to implement with fixed-point math, not offering the computational advantages that FIR filters do for multi-rate applications, being more susceptible to the noise that limit cycles and calculations generate. Due to the lack of design information for digital IIR filters, a corresponding analog design is usually completed first for new filter designs. Once created and tested, the corresponding digital filter is made, which results in additional overhead costs for making a new IIR digital filter.
How are IIR Filters Used?
IIR filters are typically used in systems that use digital signal processing. IIR filters include the Butterworth, Bessel, and Chebyshev filters. These filters are typically used in audio applications such as speakers and for sound processing functions.
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- Chebyshev Filter
A Chebyshev filter can either be analog or digital, and is an improvement on the Butterworth filter as it has a steeper roll-off and a greater passband and stopband ripple. These filters minimize overall error between actual and idealized filter characteristics for the designed range of the filter. The filter was named after Pafnuty Chebyshev, [...]...
- Butterworth Filter
A Butterworth filter is a signal processing filter that has an extremely flat frequency response in the passband. It is referred to as a maximally flat magnitude filter and is commonly used in both analog and digital audio crossover filters in home, commercial, and car stereo systems. Who Invented the Butterworth Filter? British engineer, Stephen [...]...
- Bessel Filter
A Bessel filter is a linear filter that is used in electronics and signal processing and has a flat group delay (also referred to as a maximally linear phase response). These filters are commonly used in audio crossover systems and preserve the wave shape of any filtered signals across the group delay in the passband. [...]...
- DSL Filter
A DSL filter is an analog device that improves a DSL connection by minimizing telephone signal interference with the DSL system. When installed, it acts as a barrier to prevent low frequency telephone signals to interfere with the high frequency ADSL system and vice versa. How DSL Filters Work Telephone signals usually range from 300 [...]...
- What is a Spam Filter?
A spam filter is a piece of software that filters incoming email to separate unwanted email–junk email commonly referred to as spam–and normal, desirable email. Spam is something that no one wants because, while it is annoying, it can also hold viruses, malware and other programs that can do considerable damage to one's computer. Therefore, [...]...