First, Second and Higher Order Filter Design Using Current Conveyors - Current Conveyors: Variants, Applications and Hardware Implementations - page 173

Fig. 6.41 MOSFET-C
integrator proposed by Liu
et al. [ 37 ]

V 1

C 2

y

V GA

z

V GB

CCII-

x

V 0

C

V 2

For the use of an alternative MOSFET-C integrator using CCII+ (along with
voltage buffer) in the design of a sixth order ladder filter, the reader is referred
to [ 65 ].

6.2.6 Higher Order Active Filter Design

In this section we outline some exemplary methods of designing higher order active
filters using current conveyors from amongst a number of such techniques and
circuits reported in literature such as those in [ 29 , 35 , 38 - 40 , 41 , 51 , 54 , 55 , 72 , 82 ,
89 - 91 , 93 , 107 , 108 , 113 , 145 , 164 ].

Senani ' s method of incorporating non-ideal simulated inductors and FDNRs
into higher order filter design: A number of CC-based grounded and floating
inductance simulation circuits have been described in Chap. 5 of this monograph.
Of course, such circuits can be easily used to design active filters from passive LC
prototypes by replacing passive inductor of the prototype LC ladders by
CC-simulated inductors and FDNRs. It has been recognized that lossy inductors/
FDNRs can be realized more economically than their ideal counter parts. Four new
transformations were proposed by Senani in [ 35 , 38 ] which make it possible to
incorporate even such non-ideal simulated immittances as direct elements in the
design of active filters based upon LC ladder filters.

In this sub-section, we consider one of these transformations which make it
possible to incorporate even non-ideal (lossy) simulated inductance and FDNR
elements directly into the design of active filters. Table 6.2 shows one of the
transformations (T2: F(s) s/(1 + s)) from [ 35 , 38 ] wherein it has been shown

how R, L and C will be transformed if their impedances are multiplied by this
particular frequency dependent scaling factor F(s).
The main advantage of this method is that it requires only n number of CCII

¼

s

for converting an nth order LC filter into an nth order CCII based active filter.

The practical workability of this method had been demonstrated in [ 35 , 38 ] using
CCII

implementations based on op-amps and OTAs discussed in Chap. 2 of this
monograph (see Fig. 2.3a and reference [3] therein).