Analog Filter Design Revisited: Circuit Configurations Using Newer Varieties of CCs - Current Conveyors: Variants, Applications and Hardware Implementations - page 381

12.2.2 Filter Design Using DDCC

A DDCC can be considered to be an extended version of DVCC with one additional
input terminal thereby making V x ¼

V y2 +V y3 ). This provides the feasibility
of adding and subtracting signals without requiring any external resistor(s) or
additional hardware and thereby offers additional degrees of freedoms in a number
of applications. A DDCC is characterized by the following hybrid matrix:

(V y1

2
4

3
5

2
4

3
5

2
4

3
5

I Y 1
I Y 2
I Y 3
V X
I Z

V Y 1
V Y 2
V Y 3
I X
V Z

00000
00000
00000
1 1100
000

¼ ð 12 : 69 Þ

10

where plus and minus signs represent DDCC+ and DDCC respectively.

Ibrahim-Kuntman-Cicekoglu all pass filter As an example, we present a
canonic implementation of first order APF in Fig. 12.17b which has been possible
because of capability of the DDCC and is a special case of the general schematic of
Fig. 12.17a .

Using ideal DDCC+ as shown in Fig. 12.17 , a routine circuit analysis yields the
following voltage transfer function:

V o
V i ¼

sCR 1

ð 12 : 70 Þ

sCR þ

1

and the phase is given by

2 tan 1 ʦðÞ¼ 180 ð ω CR Þ ð 12 : 71 Þ

An alternative APF by Horng-Hou-Chang-Lin-Shiu-Chiu Another first-order
APF using same number of active and passive elements as in Fig. 12.17 was
proposed by Horng et al. [ 37 ]. However the circuit suffers from a lack of high
input impedance. A routine circuit analysis of Fig. 12.18 yields the following
voltage transfer function:

V out
V i ¼

1 sCR

ð 12 : 72 Þ

1 þ sCR

From equation ( 12.73 ), the phase of this first-order APF can be determined as:

2 tan 1

ʦðÞ¼ ð ω CR Þ ð 12 : 73 Þ