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DDCC
V out
z+
x
y 2
3
y 3
y 1
V in3
DDCC
DDCC
y 1
y 2
1
y 1
z+
V in1
z+
y 2
2
y 3
y 3
x
C 2
C 1
x
V in2
R 2
R 1
Fig. 12.20 Universal filter proposed by Chiu and Horng [ 41 ]
V in1 ¼
V in2 ¼
V in3 ¼
V in . Hence, the circuit can realize all the filter responses. The
filter parameters
ˉ 0 and Q 0 for all the cases can be given by:
r
1
C 1 C 2 R 1 R 2
r
C 2 R 2
C 1 R 1
ω 0 ¼
and Q 0 ¼
ð
12
:
78
Þ
An extended version of this circuit with the provision of multiple outputs thereby
introducing additional degrees of freedom while employing same number of active
and passive elements as in Fig. 12.20 has been subsequently described by Horng
in [ 46 ].
Ibrahim-Kuntman biquad A dual output DDCC (DO-DDCC) based filter circuit
for realizing differential VM KHN biquad with high common mode rejection ratio
(CMRR) and high input impedance was presented by Ibrahim and Kuntman
[ 34 ]. The configuration (shown in Fig. 12.21 ) uses three DO-DDCCs, two grounded
capacitors and five grounded resistors. The various filter functions in differential
mode (A dm ) are being given by:
R 1 s 2
Ds
R 1 C 1 s
Ds
R 1 þR 4
2
2
R 1 C 1 R 2 C 2
A dm HP
¼
A dm BP
¼
A dm LP
¼
ð
12
:
79
Þ
;
ðÞ ;
ðÞ
Ds
ðÞ
where
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