
3 0
Analog Electronics
mined solely by R. So each time we go to twice the
frequency , Xc halves and so does the PD across it.
Now 20 logio 0.5 comes to -6 (almost exactly) , so
the output is said to be falling by 6 dB per octave as
the frequenc y increases . Exactly at/J,, the response
is falling by 3 dB per octave and the phase shift is
then -45° as shown. The slope increase s to -6 dB
and falls to OdB as we move further above and
below fu respectivel y the phase shift tending to
-90° and 0° likewise.
The LR top-cut circuit of Figure 2.2a gives
exactly the same frequenc y response as the CR
top-cut circuit of Figure 2.1a, i.e. it has the sam ...