help~~How to design such a highpass filter in MATLAB

high pass filter matlab

Hi, I am a beginner in this field. I'm in a project and need to design a highpass filter. It is used to remove the DC offset. It has a cutoff frequency 2Hz, also needs enough attenuation about 30dB. I try to design it in the MATLAB used FDATOOL. But I failed~~~can I use the butterworth method or something else

So thanks for your response!


Added after 1 hours 3 minutes:

waiting~

Added after 40 seconds:

waiting

matlab high pass filter

wqy1985 said:

Hi, I am a beginner in this field. I'm in a project and need to design a highpass filter. It is used to remove the DC offset. It has a cutoff frequency 2Hz, also needs enough attenuation about 30dB. I try to design it in the MATLAB used FDATOOL. But I failed~~~can I use the butterworth method or something else

Click to expand...

It´s not easy to answer because I don´t know what your problem resp. question is.
Of course you can design a highpass with Butterworth or any other response.
But the most important inputs for finding a circuit are:
- which frequency has to be suppressed and by how many dB ?
- Which frequencies should pass ?
- Do you need gain (active or passive design)?
- lumped elements or integrated design ?
- tunable or fixed response ?

Hint: There are many filter design programs available to support you during design (required filter order and dimensioning).

butterworth high pass filter matlab

So thanks for your help, but I really don't know much of it. This highpass filter used in a digital filter(decimator) for sigma-delta ADC. I have designed the CIC, unsinc and fir filter with matlab. But in a similar design I find there has a highpass filter at the end of the digital filters in which it just says the highpass filter is used to eliminate the DC offset. So i just want to add this highpass filter in my design to see what will happen. But I don't know how to design such a filter, I just try in the FDAtool. But I failed. Is the cutoff frequency 2Hz too small to achieve? I could't get a 2Hz cutoff frequency and the nearly -30dB attuation together. can you tell me which design method in matlab is mostly suit such highpass filter?

matlab highpass filter

As far as I have understood the contents of your inquiry, you need a highpass just to suppress the dc component of a signal, right ?
In this case, a simple coupling capacitor of appropriate value should do the job.
Together with the input R of the next stage this creates a highpass of 1st order.
What is the minimum frequency which must pass through the filter ?

high pass matlab

thanks for your response.
maybe the minimum frequency must pass through the filter is 3-5Hz. I'm not sure now. I forget to say that the input frequency is 48kHz, so is it hard to use the iir or fir filter to do it? maybe you are right. the coupled capacitor is a better choice. I just used the equiripple method to design a highpass filter in matlab. I attach the figure below. It is so hard to implement in hardware because the FIR needs 11418 taps, the attenuation is too small either.

how to use high pass filter in matlab

mostly for removing DC offset voltage, we normally use a capacitor in the way of the signal;
this automatically removes the DC offset voltage

matlab program for high pass filters

wqy1985 said:

thanks for your response.
maybe the minimum frequency must pass through the filter is 3-5Hz. I'm not sure now. I forget to say that the input frequency is 48kHz, so is it hard to use the iir or fir filter to do it? maybe you are right. the coupled capacitor is a better choice. I just used the equiripple method to design a highpass filter in matlab. I attach the figure below. It is so hard to implement in hardware because the FIR needs 11418 taps, the attenuation is too small either.

Click to expand...

Up to now I never have heard that somebody has used a digital filter only to remove a dc component.

highpass filter matlab

I get it. So thanks for your help