14 Facts About Low-pass filter

Low-pass filter is a filter that passes signals with a frequency lower than a selected cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency.

The desired filter is obtained from the prototype by scaling for the desired bandwidth and impedance and transforming into the desired bandform.

Low-pass filter is used as an anti-aliasing filter prior to sampling and for reconstruction in digital-to-analog conversion.

An ideal low-pass filter completely eliminates all frequencies above the cutoff frequency while passing those below unchanged; its frequency response is a rectangular function and is a brick-wall filter.

An ideal low-pass filter can be realized mathematically by multiplying a signal by the rectangular function in the frequency domain or, equivalently, convolution with its impulse response, a sinc function, in the time domain.

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However, the ideal Low-pass filter is impossible to realize without having signals of infinite extent in time, and so generally needs to be approximated for real ongoing signals, because the sinc function's support region extends to all past and future times.

Whittaker–Shannon interpolation formula describes how to use a perfect low-pass filter to reconstruct a continuous signal from a sampled digital signal.

Time response of a low-pass filter is found by solving the response to the simple low-pass RC filter.

Effect of an infinite impulse response low-pass filter can be simulated on a computer by analyzing an RC filter's behavior in the time domain, and then discretizing the model.

For minimum distortion the finite impulse response Low-pass filter has an unbounded number of coefficients operating on an unbounded signal.

The frequency response of a Low-pass filter is generally represented using a Bode plot, and the Low-pass filter is characterized by its cutoff frequency and rate of frequency rolloff.

The term "low-pass filter" merely refers to the shape of the filter's response; a high-pass filter could be built that cuts off at a lower frequency than any low-pass filter—it is their responses that set them apart.

Resistor–inductor circuit or RL Low-pass filter is an electric circuit composed of resistors and inductors driven by a voltage or current source.

The RLC Low-pass filter is described as a second-order circuit, meaning that any voltage or current in the circuit can be described by a second-order differential equation in circuit analysis.