
Passive signal processing and signal transmission 127
are virtually open-circuit), whilst at very high
frequencies it suffers a 18(f phase shift. At some
intermediate frequency the phase shift is 90°, and
the input impedance Z„ turns out to be constant
and resistive and equal to
V(L/C) .
Figure 5.8e
shows what is going on at a radian frequency
ω = 1/V(LC): as everything in a balanced circuit
is symmetrical, only one half of the circuit need be
shown, which makes for clarity. To ease matters
further, everything has been normalized to unity,
so that
V ,
= ±1 V = -
V ,
and X,, and A'f both equal
unity, as does the full load resistance /?„. As