Hardware Implementations of CCs Using Off-the-Shelf ICs - Current Conveyors: Variants, Applications and Hardware Implementations - page 25

Fig. 2.11 Wilson ' s
implementation of CCII+
employing an OMA+ [ 7 ]

+V

Q 3 Q 4

Q 1 Q 2

I p

i y

I p

Y
X

+

Z

−

I n i z = i x

i x

I n

Q 5 Q 6

Q 7 Q 8

−V

By adding one more pair of current mirrors and a cross-coupling a CCII is

created as shown in Fig. 2.12 .
A typical circuit made from CA3096AE mixed transistor arrays and LM301
op-amp with a compensating capacitor of 39 pF exhibits a small signal bandwidth
of greater than 1 MHz which is only restricted by the PNP transistors performance

beyond this region. Transfer distortions around 68 to 70 dB can be expected
depending upon the load. The X- terminal exhibits an effective parasitic capaci-
tance of about 4 pF whose effect on the circuit performance can be reduced by good
circuit layout techniques [ 8 ].

'

2.2.9 CCII Implementation Using Op-Amps and Only NPN
Transistors

A circuit which requires only NPN transistors but two op-amps instead of one is
shown in Fig. 2.13 which avoids use of PNP transistors and the associated fre-
quency limitations which are now only limited by the performance of the op-amps
employed. This circuit is based upon the operational mirrored amplifier proposed
by Huijsing and Veelenturf [ 5 ].