First, Second and Higher Order Filter Design Using Current Conveyors - Current Conveyors: Variants, Applications and Hardware Implementations - page 165

CCII+

y

z

x

R a1

CCII- CCII+

y y

x

z

z

CCII- x

y

R b0

z

R b2 R a2

x

CCII+

R b1

CCII+

I 0

CCII+

V 3

y

V 2

z

y

y

x

z z

V 1

x

x

R a0

I in

R 1 C 1

C 2

R 2

Fig. 6.34 A multipurpose active biquad based on CCIIs proposed by Sun and Fidler [ 28 ]

Figure 6.34 shows an exemplary multi-purpose CCII-RC biquad filter homolo-
gous to the traditional KHN-op-amp biquad proposed by Sun and Fidler in [ 28 ].
Assuming ideal CCs, a routine circuit analysis yields

the following

transimpedance and current transfer functions:

s 2 C 1 R 1 C 2 R 2

V 1
I in ¼

ð Þ V 2

I in ¼

sC 1 R 1 ð Þ V 3

I in ¼

1
Ds

ð 6 : 49 Þ

;

ðÞ ;

Ds ðÞ Ds ðÞ

s 2 C 1 R 1 C 2 R 2

1
R a 2

þ sC 1 R 1

1
R a 1

þ

1
R a 0

and I out

I in ¼

ð 6 : 50 Þ

Ds ðÞ

1
R b 2

1
R b 1

1
R b 0

s 2 where Ds ðÞ ¼ C 1 C 2 R 1 R 2 þ sR 1 C 1 þ ð 6 : 51 Þ

The various CM filter functions can be realized as follows.

1
R a 1

sC 1 R 1

1
R a 0
Ds

I LP
I i ¼

I BP
I in ¼

for R a 1 ¼ 1 ¼

R a 2 ;

for R a 0 ¼ 1 ;

ðÞ Ds ðÞ

s 2

1
R a 2

C 1 R 1 C 2 R 2

R a 2 I HP

¼

I in ¼

for R a 0 ¼ 1 ¼ R a 1 ð 6 : 52 Þ

Ds ðÞ