Biomedical Engineering Reference
In-Depth Information
Since the two resistors retain their values, the phasor drawing of the circuit is shown in the fol-
lowing figure with the ground at the lower node.
1
+
1
Ω
+
−
1
2
Ω
V
s
= 50
−
90
V
I
s
= 20
20
−
j
Ω
j
2
Ω
V
−
Writing the node-voltage equation for node 1 gives
Collecting like terms, converting to rectangular form, and converting to polar form gives
The steady-state solution is
76
v
¼
15
:
6 cos 10
ð
t
Þ
V
9.13 ACTIVE ANALOG FILTERS
This section presents several active analog filters involving the op amp. Passive analog
filters use passive circuit elements: resistors, capacitors, and inductors. To improve perfor-
mance in a passive analog filter, the resistive load at the output of the filter is usually
increased. By using the op amp, fine control of the performance is achieved without increas-
ing the load at the output of the filter. Filters are used to modify the measured signal by
removing noise. A filter is designed in the frequency domain so the measured signal to
be retained is passed through and noise is rejected.
