Biquad is referred to either analog or digital second order filters

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### What procedure to find the parameters of a given filter prototype to fit a desired frequency response?

To model the frequency response of a system, I am looking for a method to fit the response of cascaded bi-quad filters to the response of that system using an optimization algorithm. The $S$-domain ...
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I am trying to implement in python/Scipy the biquad filter with the following S-domain transfer function: $$H(s)=\frac{w_0^{2N-1}(s+w_z)}{[s^2+(w_0/Q)s+w_0^2]^N}$$ My problem here is that because of ...
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### Discrepancy in frequency response of biquad filter (in Python)

I have written a simple biquad filter class but when I check its frequency response, I get different results with different methods. If I check it "empirically" (by taking the FFT of its ...
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### What is the $Q$ of successive Second-Order Sections of an $N$th-order Butterworth low-pass filter?

What if you had an $N$th-order Butterworth lowpass filter filter with -3 dB frequency of $\Omega_0$? $$\Big| H(j\Omega) \Big|^2 = \frac{1}{1 + \left(\frac{\Omega}{\Omega_0}\right)^{2N}}$$ The number ...
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### ELI5: How do biquad filters like bandpass "know" the frequency of a signal?

I understand the code behind biquads, but I fail to understand how 5 coefficients in a biquadratic formula can isolate frequencies so precisely, especially considering it only takes the last two ...
1 vote
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### High pass biquad cascade transposed direct form II low frequency accuracy

I'm quite new to DSP and I'm trying to implement high pass biquad cascade in transposed direct form II. Currently my implementation has very poor accuracy at cutoff frequencies that are less than 5kHz ...
144 views

### How to optimally normalize filter coefficients?

I have designed an IIR filter in Matlab that comprises the following biquads ...
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### Derive Time-Domain Biquad Coefficients from Z-Domain

I'm trying to derive the time-domain coefficients of a biquad filter based on its z-domain coefficients. The purpose is to import externally-generated EQ filters (in z-domain) into Max/MSP (in time-...
1 vote
263 views

I am implementing EQ lines in my filter. I need to do biquad with slope 24 db/oct, 36/oct and bigger so I would like to cascade several biquads. I am stuck with calculating frequency response of two ...
159 views

### Direct form 1 filter equation for a biquad filter

In general, we all know that the direct form 1 equation for a biquad filter is given by $$y(n) = b_0x(n) + b_1x(n-1) + b_2x(n-2) - a_1y(n-1) - a_2y(n-2)$$ But when it comes to practical applications ...
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