
Tricks of the trade 277
impedance and 1 radian/second cut-off frequency
to,
say 50 Í1 and 200 kHz, in two simple stages.
First, to renormalize the impedance level to 50 Í1,
the capacitor values are all divided by 50 and the
values of the inductors are multiplied by 50; we
now have a 50 Π filter but still with a cut-off
frequency of
1/27τΗζ.
This is now scaled to
200 kHz by dividing both capacitor and inductor
values by 1 256 000, i.e. by 2ττ x 200 x 10\
Signal levels are another variable which can
conveniently be normalized, the obvious choice
being
1
V DC or
1
V AC RMS, as the case may be.
Provided that we are dealing with linear circuits