Laboratory Manual - King Fahd University of Petroleum and Minerals

Bandpass realization
A circuit that realize biquadratic BPF based on a single op amp is shown in Figure 3
known as Delyiannis-Friend biquad
v s
R 1
C 1
R 2
R 3
C 2
2
3
7
-
741
+
+Vcc
4
-Vcc
6
v o
T
BP
v
() s
Figure 3: A second-order BPF based on a single op amp.
s / C R
o
1 1
2
vs
s s( C1 C2) /( C1C 2R2 ) ( R1 R3 ) / C1C 2R1R 2R3
Therefore, the filter parameters are as follows:
1/ C1R1 C2R2
a) gain=
( C C ) / C R C R ( C C
)
b) w
o
1 2 2 2 1 1 1 2
R
R
1 3
C C R R R
1 2 1 2 3
o
( C C )
BW w
Q C C R
c)
1 2
1 2 2
d)
w R R C C R
o
Q BW RR C C
1 3 1 2 2
1 3
1 2
PRELAB WORK
Students must perform the following calculations and SPICE before coming to the
lab.
Design:
1. Design the circuit of Figure 1 such that f o =12.5kHz, Q=5, the dc gain is not specified.
Use C 1 =C 2 =C and R 1 =R 2 =R.
2. Design the circuit of Figure 3 to achieve f o =10kHz, Q=3 and gain of 5. Use
C 1 =C 2 =5nF.
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