A high-pass filter (HPF) 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. It is sometimes called a low-cut filter or bass-cut filter in the context of audio engineering.

A capacitor can be used as part of a high pass, low pass, or band pass filter, depending on how it’s connected to other parts. For example, a capacitor with a resistor can be a high pass filter: or a low pass filter: Even that by itelf is not a filter, since just a changing impedance isn’t a filter.

Here bandwidth of the filter denotes the value of frequency from which signals are allowed to pass. For example, if the bandwidth of the high pass filter is given as 50 kHz it means that only frequencies from 50 kHz to infinity are allowed to pass.

A high pass filter is a filter which passes high-frequency signals and blocks, or impedes, low-frequency signals. In other words, high-frequency signals go through much easier and low-frequency signals have a much harder getting through, which is why it’s a high pass filter.

This additional resistor helps to prevent “turn on thump” when we try to connect the load. And sometimes we add this “extra” resistor simply becaues R_load has a very high resistance (almost ideal case). So we need this resistor to determine the cut-off frequency.

The current flowing out of the power supply is just the voltage (5 volts) divided by total resistance, I=V/R, so:

1. I=5R+RLED.
2. 2=IR=5RR+RLED.
3. VR=VRR+RLED.

A filter is a circuit whose transfer function, that is the ratio of its output to its input, depends upon frequency. High-pass filters allow signals above a characteristic frequency to pass unattenuated or even amplified. Band-pass filters allow frequencies in a particular range to pass unattenuated or even amplified.