Sampling and Reconstruction of Analog Signals
Sampling and Reconstruction of Analog Signals
Sampling and Reconstruction of Analog Signals
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Practical D/A converters<br />
• Zero-order-hold (ZOH) interpolation:<br />
<br />
<br />
In this interpolation a given sample value is held for the<br />
sample interval until the next sample is received.<br />
It can be obtained by filtering the impulse train through an<br />
interpolating filter <strong>of</strong> the form<br />
xˆ<br />
h<br />
a<br />
0<br />
( t)<br />
=<br />
⎧1<br />
( t)<br />
= ⎨<br />
⎩0<br />
x(<br />
n),<br />
nT<br />
0<br />
≤<br />
s<br />
t<br />
≤<br />
≤ T<br />
s<br />
otherwise<br />
n ≤ ( n + 1) T<br />
• The resulting signal is a piecewise-constant (staircase) waveform which<br />
requires an appropriately designed analog post-filter for accurate<br />
waveform reconstruction.<br />
x (n)<br />
xˆ<br />
a<br />
( t)<br />
x a<br />
(t)<br />
ZOH<br />
s<br />
Post-Filter
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