Second Generation Controlled Current Conveyors (CCCII) and Their Applications - Current Conveyors: Variants, Applications and Hardware Implementations - page 288

9.14 CCCII-Based Precision Rectifiers

Full wave precision rectifiers have been proposed in literature using a variety of
building blocks such as op-amps, current conveyors and current feedback op-amps.
A circuit to realize a precision rectifier using CCCIIs was presented in [ 43 ] which
employ a pair of complimentary MOS transistors and two resistors in addition. This
circuit is shown in Fig. 9.44 .
The lower CCCII provides a current output proportional to the input voltage.
This creates a controlled voltage at the gates of the two MOSFETs in conjunction
with the resistor R which is so selected that both the transistors remain in saturation
even for small input signals. Depending upon whether V in is positive or negative,
the gate voltage V G would be either +V or -V (this requires that the ratio R/R x1 is
large which can be achieved by proper choice of I B1 and R). Here V denotes the

DC biasing supply voltage of the CCCIIs. An analysis of this circuit shows:
For

2 I B 2 R L
V T

V in > 0, V G ¼ þ V , V o ¼ V in ð 9 : 59 Þ

and for

2 I B 2 R L
V T

V in < 0 V G ¼ V , V o ¼ V in ð 9 : 60 Þ

:

An important merit of this circuit is that the output amplitude of this rectifier is
electronically controllable by external bias current I B2 .

I B2

M n

Z+

V in

Y

V 0

Z−

X

R L

M p

I B1

Y

Z+

2

X

R