Analog Filter Design Revisited: Circuit Configurations Using Newer Varieties of CCs - Current Conveyors: Variants, Applications and Hardware Implementations - page 414

s

1
C 1 C 2 R 1 R 2

¼

ω 0
Q 0

1
C 1 R 1 ;

angular frequency ˉðÞ¼ bandwidth ð 12 : 160 Þ

;

r

C 1 R 1
C 2 R 2

r 2
r 1

quality factor QðÞ¼ and H 0 LP ¼ H 0 HP ¼ H 0 BP ¼ ð 12 : 161 Þ

Band stop (BS) and all pass (AP) responses can be realized (in all cases) by
summing (I 01 and I 03 ) and (I 01 ,I 02 and I 03 ) respectively. The transfer functions
thus obtained are given by:

r 1 s 2 C 1 C 2 R 1 R 2 r 1 s 2 C 1 C 2 R 1 R 2

r 2 r 2

þ 1 sC 2 R 2 þ 1

I 04
I in ¼

I 05
I in ¼

ð 12 : 162 Þ

;

Ds ðÞ Ds ðÞ

This is to be noted that in all the four biquads, no realization constraints are required
in BS and AP realizations. Also, in all the responses Z in is resistive (equal to r 2 ),
however, by using an additional MOCC as a current follower (CF) with virtual
ground at its input, all four filter configurations can be modified to yield ideal zero
input resistance. The configuration of Fig. 6.25d is convertible into an electronically
controllable biquad by connecting the x-terminal of all the three MOCCs to ground
thereby eliminating (due to being short circuited) r 1 ,R 1 and R 2 and using in their
places the parasitic input resistances of the three MOCCs namely, R x1 ,R x2 and R x3 .
The details of the resulting circuit would be presented subsequently in Chap. 10 .

Senani-Singh SIMO-type universal CM biquad The SIMO-type universal CM
biquad presented by Senani and Singh [ 125 ] is shown in Fig. 12.46 . The proposed
circuit uses only three MOOCs, four grounded passive elements and is capable of
providing all five standard filter functions without requiring any component-
matching conditions or change of terminals/active elements. The filter parameters
ˉ 0 and bandwidth are orthogonally tunable.
Assuming MOCCs are to be defined by i y ¼ 0, v x ¼ v y ,i z + ¼

+ and i z ¼ i x ,a
routine analysis of the circuit yields the following transfer functions:

i

x

s 2 C 1 R 1 C 2 R 2
Ds

I LP
I in ¼

1
Ds

I BP

I in ¼

sC 1 R 2 ð Þ I HP

I in ¼

ð 12 : 163 Þ

ðÞ ;

;

Ds ðÞ ðÞ

Furthermore, additional inverting HPF and inverting LPF current outputs are
realizable from Z-terminals of MOCC-1 and MOCC-3 respectively. Finally,
notch is realizable by adding I HP and I LP and AP is realized by summing I BP also,
thereby yielding

s 2 C 1 R 1 C 2 R 2 þ s 2 C 1 R 1 C 2 R 2

I notch
I in ¼

1 I AP

I in ¼

sC 1 R 2 þ 1

ð 12 : 164 Þ

;

Ds ðÞ Ds ðÞ

where