Sallen-Key filter | multiple feedback filter | state variable filter | Biquad filter

This page covers Sallen Key filter multiple feedback filter vs state variable filter vs Biquad filter and mentions low pass filter and high pass filter equivalents of these second order filter types. It mentions sallen-key low pass filter, sallen key high pass filter, multiple feedback low pass filter, multiple feedback high pass filter, 2 pole state variable filter and standard 2 pole biquad filter as well as high pass equivalent of it. All these filters are based on Operational Amplifier inverting and non-inverting combinations. Refer inverting vs Non-inverting Op-Amp for more information.

Sallen Key low pass filter

sallen key filter low pass type

The figure-1 depicts sallen key low pass filter using Op-Amp. It also mentions transfer function of this filter.

Sallen Key high pass filter

sallen key filter low pass and high pass type

The figure-2 depicts sallen key high pass filter with 2 poles. It also mentions low pass equivalent of this high pass filter.

multiple feedback filter low pass type

multiple feedback filter low pass type

The figure-3 depicts multiple feedback filter of low pass type.

multiple feedback filter high pass type

multiple feedback filter high pass type

The figure-4 depicts multiple feedback filter of high pass type.

state variable filter 2 pole type

state variable filter

The figure-5 depicts state variable filter 2 pole type.

Biquad filter 2 pole type

Biquad filter

The figure-6 depicts standard 2 pole biquad filter and high pass filter of biquad type.

Filter RELATED LINKS

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Link to Op-Amp and other electronic components

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Ohm law
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What is Difference between

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RF and Wireless Terminologies