# Questions tagged [high-pass-filter]

A high-pass filter is an electronic filter that passes signals with a frequency higher than a certain cutoff frequency and attenuates signals with frequencies lower than the cutoff frequency.

219 questions
Filter by
Sorted by
Tagged with
55 views

### Can the impedance of the source affect the response of a high-pass filter?

Having a simple RC high-pass filter, can a high signal impedance change the cutoff frequency response? Or more practically, should a resistor before the capacitor be included in the calculation for ...
• 53
41 views

### Plotting the bode plot of a high pass filter using matlab

I am trying to theoretically find the frequency response of the circuit given below: Firstly i found the impedance value of the RC Ladder by applying the equation below, then i defined this as "...
64 views

### What happens if a low-pass filter and a high-pass filter are interchanged in a band-pass filter?

what happens in this circuit if I interchange the highpass filter and lowpass filter how does it affects the gain and phase shift
• 33
143 views

### RC high-pass filter is blocking all current instead of just removing the DC offset

I am trying to simulate a simple current mirror, which accepts an AC current with a DC offset making the entire signal positive, so that it is properly mirrored (the signal was being cut off for ...
1 vote
61 views

### How to determine the transfer function of this pi filter?

I have this pi filter, I wonder how do i determine the dynamic model and the transfer function of this filter?
• 11
85 views

### Finding transfer function of high-pass circuit

I've already done the calculations myself, but I am getting a completely wrong answer for the poles and zeros. I'm not sure what I am doing wrong. If someone could point out my mistake please I would ...
• 69
1 vote
43 views

### How can I calculate filter parameters between RF switch and antenna?

In the schematics en.MB1389-WL55JC-highband-E02_Schematic, there's a Pi filter following the RF switch before it links to the SMA connector for the antenna. Upon calculation, I found that the cutoff ...
• 185
133 views

### Differential amplifier op-amp schematic connection and DC biasing

I have a differential IF (intermediate frequency) signal generated by an ADL5801 RF mixer. Stage 1: the signal is amplified before active filtering and it has LC LPF in the beginning for filtering ...
• 75
67 views

### My Sallen Key Butterworth high pass filter's frequency response graph is not responding

I tried to make a cutoff frequency of interface in partial discharge but the response frequency graph is not responding. I already changed (Amplitude= & frequency= 50Hz) in the sine generator ...
1 vote
87 views

### Active passband filter with higher gain than open loop

I'm desgining an active band pass filter using a LM324 op amp. The signal I need to amplify is centered on 20kHz and has a width of around 1kHz. Looking at the open loop gain of the LM324 I see that ...
97 views

### Transfer function in a 6th order Butterworth Filter

Design the next High-Pass Butterworth filter: 3db attenuation at 2000Hz 80db minimum attenuation at in 400Hz i know that 2000hz is my 3db cutoff frequency and 400hz my sampling frequency. Therefore,...
1 vote
42 views

### Alternate values of high pass filter isn't working, even though gain, phase & transient response is almost same

I'm trying to design a high pass filter to remove the humming noise (around 50-60Hz.) If I use alternate values, it's not working. It's the recommended value from a YouTube video (470pF, 5.6Mohm.). ...
127 views

### High pass filter after TIA is not behaving as expected in LTspice

I have the following schematics to amplify a current signal modulated at 10 kHz. The first stage is a transimpedance amplifier with a -3dB bandwidth of 72 kHz. The second stage is a high pass filter ...
58 views

### Is it good to equalize input impedances in cascade active opamp filters?

In my design, I designed a first 2nd order high pass filter with a Sallen key cut-off frequency of 0.2Hz and an input impedance of 250kohm. Then, I designed a second-order Multiple-Feedback low pass ...
• 756
90 views

### Non-constant active filter gain

I designed an amplifier using an instrumentation amplifier and an operational amplifier. Here, I used a 2 Hz high pass and 100 Hz multi feedback low pass filter, but I could not get the efficiency I ...
73 views

### LTC 2065 is not working between 2 V - 4 V power supply

I'm having a problem with the LTC2065 operational amplifier design. I use a 3.3V supply as I show in the picture, and after boosting my input signal I make it oscillate at 1.8V using a 1.8V virtual ...
125 views

### First order RC highpass filter input capacitance

I'm trying to find the capacitive load repreented by an RC first order highpass filter. Intuitively, I tend to believe the load will not be the C series capacitance, since the capacitor is not being ...
• 577
87 views

### What is this following filter circuit called? (For amplifiers)

Noob here. I have a doubt on these passive low and high pass filters for amplifiers. If this is called high pass filter (which is doubled in series), then what is this filter circuit called? Here's ...
182 views

### Are RC /CR - Highpass filter the same?

I‘m quite new to electrical engineering and one of the tasks is to showcase and plot an CR high pass filter. I am familiar with RC HP filters but this is new to me. Just changing the order of the ...
1k views

### What is the coil for in these cheap tweeters?

I disassembled a cheap tweeter because I wanted to use only the inner part of it since it is just about 5mm tall (1/4 inch). I thought the coil that surrounds it was just a cheap inductor to "...
• 285
69 views

### I want to implement a 2-active crossover circuit with LM833 and amplify it using LM386 and now the problem is I couldn't understand the circuit [closed]

I can understand up to certain level that we used a buffer, low pass filter but I can not connect with circuit and coming to components we used 120 Ω, 6.8 nF for active crossover with power supply + ...
51 views

### HP filter for MHz pulses

I need a high pass filter for my measuring setup and I'am a total newbie to analog filters. I have weak hf pulses (0.5-1.2 MHz, 10 mV) superimposed on lf sine wave (8-40 kHz, up to 5 V), I'm ...
1 vote
200 views

### Filter out one square wave while retaining the other

I have two square wave signals. The first signal has a frequency around 10 kHz, while the other signal has a higher frequency of about 50 kHz. How can I filter out the lower frequency signal without ...
• 11
339 views

### Why do my high and low pass filters look like high pass filters in LTSpice plot?

I am new to this and trying to learn about designing analogue audio filters. I looked at a couple of tutorials online that gave examples about how to implement and simulate high and low pass filters. ...
1 vote
120 views

Theoretical question: I have seen in many analog signal circuits that the analog input pin is pulled down through a resistance. Sometimes it is also pulled up and sometimes there is a capacitor ...
56 views

### Frequency response and phase response

In filters there is frequency response and phase response but why we consider these two parameters. What is the significance of these responses in practical applications? In Bessel filters, after ...
• 11
110 views

### Op-amp high-pass filter and low open-loop gain at higher frequencies

How can a high-pass filter work when the open-loop gain of an op-amp completely attenuates from a certain frequency? I understand that the open-loop gain of an op-amp is what limits every closed-loop ...
117 views

### My LTspice simulation results don't match the breadboard

I was testing a high pass filter like this. And here comes the simulation result on LTspice as well. This is the AC analysis result followed by the transient analysis. The 8Hz transient analysis ...
• 1
1 vote
284 views

### How can I only let a specific frequency pass in an AM receiver?

I wanted to create an AM receiver and I know partly how to demodulate the signal. I know I need to use a low pass filter to get the low frequency audio signal, but I don't know how to only get data ...
59 views

### Wrong frequency response of an active HPF filter

I am trying to simulate an active high pass filter on OrCad, but the frequency response of it looks like a band pass filter, does anyone know why ?
343 views

### Cut off frequency of a passive second order low pass filter

I was trying to do a simulation for second order low pass passive filter, and the equation of the cut off frequency is $$f_c=\frac{1}{2\pi\sqrt{R_1C_1R_2C_2}}$$ when I calculate it on the values of ...
361 views

### Designing a crossover for dual woofers and a single tweeter

I recently purchased a cheap tower speaker set which has two woofers per channel. This does not have a crossover circuit as i understand and only has a filter capacitor for the tweeter. Can a three-...
• 143
105 views

I am planning on modifiying the crossover circuit in a speaker unit. and after doing some research came across a plethora of ready made crossovers available for purchase on the internet (like the one ...
• 143
536 views

### Transfer function of a 3rd-order high-pass filter

Can we take the transfer function of the below 3rd-order high-pass filter as $$\left (\frac{R}{R+\frac{1}{j\omega C}}\right )^3$$ ? This circuit is a part of RC oscillator. To calculate the β of the ...
102 views

### Need help with pulse sensor design modification [closed]

So I've got the below pulse sensor design. I don't understand why they filter before they amplify. I'd like to modify it in a way that I amplify the signal first, LPF second, HPF last. For some reason ...
2k views

### Why do we need R1 in a non-inverting op-amp?

I am quite new to learning op-amps. What is the purpose of putting R1 there? Does this have any meaning in the design of a microphone amplifier? I read about this from another answer, which says that ...
• 91
196 views

### Will separate high-pass filters work properly with two speakers wired in parallel?

I have wall-mounted satellite speakers – inexpensive Orbs are in one room and more expensive Gallo Divas are in an adjoining room. I need to wire these speakers in parallel with high-pass filters. The ...
497 views

### 3 dB frequency of first-order active high-pass filter

Using the KCL law in the red dot in the circuit shown above, I got this equation: $$\frac{V_\text{in}}{R_1 + \frac{1}{j\omega C}} + \frac{V_\text{out}}{R_2} = 0$$ From this equation the transfer ...
1k views

### RC differentiator / RC integrator explanation (input waveform is square wave, triangular wave, sine wave)

The circuit below is an RC differentiator (RC high pass filter.) The input and output waveforms: I can understand this. Mainly due to capictor charging and discharging. How about an RC integrator (...
• 103
258 views

### Modulating a high-frequency signal to get rid of an undesired low-frequency component

So when I ask my function generator for 2 MHz, it gives me that with a 19 Hz oscillation. For my application this low-frequency signal is very problematic. I've tried high passing it which does close ...
198 views

### Lux meter 50 Hz sine noise filter

I've built the circuit with diagram: I used R1 10 MΩ instead of 50 kΩ to get a higher gain. I wanted to measure light intensity, so I'm interested in DC output ...
864 views

### Converting two cascaded first-order high-pass filters circuit to a second-order high-pass filter using Sallen-key configuration

Below is the transfer function of the two cascaded first-order high-pass filters (each with 20.6 Hz cut-off frequency) and their circuit: And then there is the transfer function of the second-order ...
• 803
115 views

### How much power passes through the shunt component of a high-pass Pi or Tee filter?

I would like to send ~100W through an RF filter. Can you estimate the current passing through the shunt component without a circuit simulation assuming a reasonably high S21 value? MLCC's are cheap, ...
• 1,996
104 views

### Chaotic Highpass Filter Output

I'm trying to build an RF transmitter circuit using LTSpice. Built a diode balanced signal mixer connected to a high pass filter to distinguish high frequency from low frequency. However, I'm kinda ...
• 399
622 views

### Concatenating first-order high-pass filters

I have the following circuit, which is an active high-pass filter with the knee frequency $f_{-3 dB} = \frac{1}{2\pi RC} = \text{1 kHz}$ I wanted to concatenate two of those systems in order to ...
• 293
46 views

### Designing a second order HPF with a high gain common-source

I have a High gain (A = 22k) Common-Source circuit, and I was wondering If I can make a second order HPF like this circuit: My circuit is just an NMOS with an input at the gate, output at the Drain, ...
• 293
573 views

### Second order active high pass filter

I am trying to design an active filter, which I assume is an active high pass filter according to what I see from the Bode plot. I can get the transfer function from this plot and then I need to ...
283 views

### Noise of low-frequency RC high pass filter preamplifier circuit with LT1028

I want to build a low-noise and low-frequency preamplifier with the first-stage opamp of type LT1028 offering an input-referred voltage noise density of about $2~\mathrm{nV}/\sqrt{\mathrm{Hz}}$ at \\$...
• 752
1 vote