Biomedical Engineering Reference
In-Depth Information
6
5
4
3
2
1
0
0
200
400
600
800
1000
1200
1400
Frequency (rad/s)
EXAMPLE PROBLEM 9.29
Using the high-pass filter in the following circuit, design the filter to have a gain of 5 and a
cutoff frequency of 100
rad
s
.
R
b
−
R
a
C
+
+
+
V
S
−
v
0
−
Solution
Since the op amp is assumed ideal and the noninverting input is connected to ground, the
inverting input is also connected to ground. The operation of this filter is readily apparent because
at low frequencies, the capacitor acts like an open circuit, so no input voltage is seen at the non-
inverting input. Since there is no input, then the output is zero. At high frequencies, the capacitor
acts like a short circuit, which reduces the circuit to an inverting amplifier that passes through
high-frequency signals.
Continued
