Hardware Implementations of CCs Using Off-the-Shelf ICs - Current Conveyors: Variants, Applications and Hardware Implementations - page 27

currents, each equal to Ip, flow in transistors Q5, Q6 and then Q4 so that at
Z-terminal, the current going in is equal to (Ip-In) and hence, equal to i x thereby
realizing a CCII+ since i y ¼ 0 and V x ¼ V y are available by virtue of the first

op-amp and its unity gain connection.

2.2.10 Current Conveyor Implementation Using New Mirror
Formulation

In reference [ 9 ], Wilson proposed a new current conveyor implementation shown
here in Fig. 2.14 in which the new mirror formulations have been shown in the
dotted boxes. This new eight transistor current mirror can be seen to be obtained by
stacking two four transistors modified Wilson current mirrors such that the output
current I 0 can be seen to be equal to the difference of two input currents I+ and I

i.e., I 0 ¼ ).

This circuit was constructed using CA3096 AE mixed transistor arrays,
LM301A op-amp with 27 pF compensation capacitor and a 4.7 K

(I + I

ʩ bias resistor

along with 15 V DC power supplies. The circuit exhibited a 3-dB bandwidth of

more than 1 MHz for all loads less than 1 K . The rise times of the order of 150 n

sec irrespective of output of magnitude were achievable for low impedance of the
order of 330

ʩ

ʩ or less. Maximum voltage slew rates greater than 15 V/ ʼ s were

obtainable greatly exceeding slewing ability of the op-amps employed.

2.2.11 Conversion of CCII into CCI and Vice Versa

In [ 14 ] Bruun demonstrated that CCI can be realized from a multiple output CCII
and on the other hand, a CCII can be similarly realized from a multiple output CCI.
In the first case, one of the Z + outputs of the CCII is returned to its Y-terminal
thereby making i y ¼ i x as shown in Fig. 2.15a .

Similarly, when one of the Z- output terminal of a multiple output CCI is
returned to its Y-terminal this creates a net current entering the terminal-Y as
zero thereby giving i y ¼

0 (see Fig. 2.15b ).

2.2.12 OMA-Based Multiple-Output CCs

Creating multiple output CCIIs (and therefrom multiple output CCIs using the
conversion method outlined in the previous section) using op-amps in supply
current sensing mode requires only additional current mirrors and is straight
forward as shown in Fig. 2.16 .