1.5 The significance of reactive components equations
25
1.5.5 Imaginary impedances are VERY real!
As explained in previous sections, impedance is a means to indicate not only the ratio of current and
voltage amplitudes but also their phase relationship. Let us illustrate this further with a simulation
carried out with AWR Microwave Office.
Let us first consider a very simple circuit which comprises of an AC voltage generator, with internal
resistance
9
R
S
= 50Ω, shown explicitly in the schematic, and an ideal capacitor as a load. This is shown
in Figure 1.5-11.
Figure 1.5-11 A simple circuit with an ideal capacitor as a load
Figure 1.5-12
Voltage and current across the capacitor at 1GHz
9
The internal impedance of a radio frequency generator is often chosen to be 50Ω
ACVS
ID=V1
Mag=1 V
Ang=0 Deg
Offset=0 V
DCVal=0 V
CAP
ID=C1
C=20 pF
RES
ID=RS
R=50 Ohm
M_PROBE
ID=VP1
0 0.5 1 1.5 2
Time (ns)
Graph 1
-0.2
-0.1
0
0.1
0.2
-20
-10
0
10
20
p2
p1
0.2227 ns
19.75 mA
0.4729 ns
0.1572 V
Vtime(M_PROBE.VP1,1)[*] (L, V)
Schematic 1
Itime(M_PROBE.VP1,1)[*] (R, mA)
Schematic 1
p1: Freq = 1000 MHz
p2: Freq = 1000 MHz
Conquer Radio Frequency
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