CMOS Implementations of Current Conveyors - Current Conveyors: Variants, Applications and Hardware Implementations - page 70

The utility of this improved CMOS CCII architecture was demonstrated by
successfully devising a band pass filter and a current controlled oscillator, tunable
in high frequency ranges: of 1.22-1.56 GHz and 290-475 MHz respectively.

4.11 Current Conveyor with High Current Driving
Capability, Operated from 1.5 V Power Supply

A CMOS CCII+ implementation with rail-to-rail input-output operation and high
deriving capability was proposed by Mita et al. in [ 38 ] and is shown here in
Fig. 4.11 . This circuit is based upon three main blocks which are: a transcon-
ductance amplifier with a differential input and two matched inverting transcon-
ductance output stages with their inputs connected in parallel. The output of one of
the inverting transconductance is fed back to non-inverting terminal of the input
transconductance thereby creating a unity voltage gain between terminals Y and X
of the current conveyor. In the schematic of Fig. 4.11 , the first transconductance
block is constructed from two complimentary differential amplifiers made from the
MOSFETs M 1 -M 2 and a PMOS current mirror (shown symbolically) and MOSFET
pair M 5 -M 6 and two NMOS mirrors (shown symbolically) along with the DC bias
current sources I B1 and I B2 . It is this part of the circuit which ensures rail-to-rail
capability. The MOSFET M 5 is configured as a common source amplifier and the
transistors M 6 ,M 7 ,M 8 ,M 11 and M 16 setup the quiescent current and help in
properly deriving the two output transconductance stages which are based upon a
topology proposed by Palumbo [ 67 ]. The MOSFETs M 6 -M 7 and M 11 , forming the
current mirror, provide the signal inversion required for the Miller compensation
which is implemented through a compensating resistor R c and compensating

+V DD

C 0 R 0 I B4

M 14 M 15

I B2

M 17 M 18

M 16

M 5 I B3

M 3 M 4

Y

Z

M 13

M 12

M 2

M 1

X

M 7

M 6

M 10 M 11

M 9

M 8

I B1

−V SS

Fig. 4.11 1.5 V CC with high current driving capability devised by Mita et al. [ 38 ]