Q3 [15 pts]: The effect of a power supply filter on the common-mode (CM) currents is sometimes characterized by the CM impedance defined as
Zc=V(c)/(I)c
, with reference to Figure 3. If
L_(GW)=1mH
,
L=28mH,k=0.98
and
C_(CL)=C_(CR)=3300pF
, use LTSPICE to plot
Z_(C)
from 150 kHz to 30 MHz , and calculate the values of
Z_(c)
as these two frequency points. Repeat this for the differential-mode ( DM ) impedance
Z_(D)
with respect to Figure 4 using
C_(DR)=C_(DL)=0.1\mu F
. [Hint: you need to specify a source value, i.e. 1 mA and then find the corresponding voltage and their ratio to get the impedance.] Figure 3 Fig.... .