Biquad Filter Coefficient Calculator

The Biquad filter is a type of digital filter that is used widely in digital signal processing, a discipline of physics and engineering. These filters are crucial in disciplines like electronics and telecommunications where sound and signal processing is key. This tutorial will explore the coefficients of the Biquad filter, the associated formula, and its real-world applications.

Biquad Calculator
Biquad Filter Coefficient Calculator Results
a0 =
a1 =
a2 =
b1 =
b2 =

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The generic transfer function for the Biquad filter is:

H(z) = (b0 + b1z-1 + b2z-2) / (1 + a1z-1 + a2z-2)


  1. H(z): is the transfer function of the filter
  2. b0, b1, b2: are the feedforward coefficients
  3. a1, a2: are the feedback coefficients
  4. z: is a complex number representing the frequency response of the filter

Who wrote/refined the formula

The development and refinement of the Biquad filter and its coefficients is a collective effort of numerous engineers and physicists over several years. It is not associated with a single individual but rather the progress in the field of signal processing.

Real Life Application

Biquad filters are commonly used in audio equalization in various sound and music applications, such as audio players, musical instruments, and sound engineering software. For example, the sound equalizer on your digital music player uses Biquad filters to modify the tonal balance of the music.

Key individuals in the discipline

One significant individual in the field of digital signal processing is Alan V. Oppenheim, a professor at MIT. His work and publications have greatly contributed to the understanding and application of digital filters, including Biquad filters.

Interesting Facts

  1. Biquad filters are fundamental in audio processing and have made significant contributions to the music and entertainment industries.
  2. Due to its versatility, the Biquad filter can implement several types of filters like low-pass, high-pass, band-pass, and notch filters by just adjusting the coefficients.
  3. The development of digital filters like the Biquad filter has revolutionized how we manipulate and interpret signals, significantly impacting telecommunications and digital media.


Biquad Filter Coefficients are a key concept in digital signal processing and play a critical role in various applications, especially in the realm of audio processing. Understanding the principles and calculations related to Biquad filters allows for more effective and nuanced manipulation of digital signals, contributing to advancements in audio technology and telecommunications.

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