reconstruction filter

In a mixed-signal system (analog and digital), a reconstruction filter (or anti-imaging filter) is used to construct a smooth analogue signal from the output of a digital to analogue converter (DAC) or other sampled data output device.Whilst in theory a DAC gives a series of impulses, in practice, the output of a DAC is more typically a series of stair-steps. The low pass reconstruction filter smooths the stair step (removes the harmonics above the Nyquist limit) to (re)construct the analogue signal corresponding to the digital time sequence.
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