About the cutoff frequency of high pass filter

起名想半天

About the cutoff frequency of high pass filter [Copy link]

 

My output signal has a DC bias, and I want to use a high-pass filter to filter it out. What is the lowest cutoff frequency of the high-pass filter? Or is it feasible to use a low-gain AC amplifier?

maychang

"What is the lowest cutoff frequency of the high-pass filter?" If cost is not a consideration, it can be arbitrarily low.

xiaxingxing

What is the frequency of your signal?

gxg1122

Can't I add a DC blocking capacitor?

maychang

gxg1122 posted on 2017-11-1 14:28 Is it not okay to add a DC blocking capacitor?

The original poster may not know that the DC blocking capacitor and the circuit input resistor after the capacitor are a first-order high-pass filter.

起名想半天

xiaxingxing posted on 2017-10-31 18:48 What is the frequency of your signal?

I just want to filter out the DC, and the high frequency can be up to more than 10 MHz. Can the low cutoff frequency be 0.01Hz?

起名想半天

maychang posted on 2017-10-31 17:18 "What is the lowest cutoff frequency of the high-pass filter?" If cost is not considered, it can be as low as desired.

I only need 0.01Hz, so for RC filtering, what are the resistance and capacitance values?

maychang

[url=forum.php?mod=redirect&goto=findpost&pid=2255221&ptid=573822]I just need to reach 0.01Hz, so for RC filtering, what value can this resistance and capacitance take?

0.01Hz, the period is 100 seconds. As long as the RC product can reach this time, it will be fine. For example, the resistance is 1 megohm and the capacitance is 33 microfarads, the time constant is already 33 seconds.

起名想半天

maychang posted on 2017-11-2 12:19 0.01Hz, the period is 100 seconds. As long as the RC product can reach this time. For example, the resistor is 1 megohm and the capacitor is 33 microfarads, the time constant is already 33...

Thanks, brother! I want to find a 1 megohm resistor and a 100 microfarad capacitor to make a high-pass filter. Is it feasible? Or are there any other restrictions?

maychang

I thought about the name for a long time and posted it on 2017-11-2 16:26 Thanks, brother! I want to find a 1 megohm resistor and a 100 microfarad capacitor to make a high-pass filter. Is it feasible? Or is there anything else...

With such a large time constant, it will take quite a long time to reach a stable state after power-on (maybe several minutes or even longer). The host should be mentally prepared.

PowerAnts

I thought about the name for a long time and posted it on 2017-11-2 16:26 Thanks, brother! I want to find a 1 megohm resistor and a 100 microfarad capacitor to make a high-pass filter. Is it feasible? Or is there anything else...

Brother? Maychang is almost as old as your grandfather. Hurry up and apologize to Maychang, haha

魔双月壁

I just encountered a similar problem a few days ago, but it didn't seem as exaggerated as yours. I connected a 0.1uf capacitor to remove the DC component and my pulse was only more than 1KHZ