Varieties of Current Conveyors - Current Conveyors: Variants, Applications and Hardware Implementations - page 332

I Z

a

C C

±K

I X

A

V Y G M1

−A V2 VF

V X

R 01

G M2

b

+V DD

M 10b

M 9b

V IT+

M 2 M 4

M 7

C c
R C

M 9 M 10

M 16b

M 7b

M 10c

M 8

V b1

M 3 M 6

Y M 1

Z

X

M 5

M 15c

M 14c

V B3

M 16

M 13b

M 15
M 15b

M 14
M 14b

V B1

V B1

V vt+

M 11 V vt− V B2 M 13

M 12

V IT−

−V SS

Fig. 10.22 The architecture and implementation of the VCG-CCII proposed by Marcellis et al. ( a )
Block diagram ( b ) An exemplary CMOS implementation (Adapted from [ 60 ] © 2009 Springer)

The three ports of the inherent CC are created as follows: A voltage follower
between ports Y and X is created by two transconductance stages, an internal
frequency compensation circuit and a voltage follower. Since the input front end
is a transconductor, its very high input impedance would imply I y ¼

0. The output
current of the voltage follower, which constitutes I x , is sensed through the technique
of power-supply-current-sensing technique applied on this voltage follower and
accordingly, the port Z is created. The two transconductors along with the com-
pensating circuitry and VF ensure that the voltage gain between ports Y and X is
electronically-controllable by the ratio of the transconductances, since

V x /V y ¼ G m1 /G m2 . The input impedance looking into the port Y is ideally infinite

leading to I y ¼ 0.

For some other, digitally-controlled Current Conveyor versions, the reader is
referred to [ 61 , 62 ].