Second Generation Miscellaneous Linear/Nonlinear Applications of Various Types of Current Conveyors - Current Conveyors: Variants, Applications and Hardware Implementations - page 506

capacitor (for the duration T 1 ) whereas on the other hand, during the discharging of
the capacitor, the roles of the diodes are reversed i.e., D 2 is ON and D 1 is OFF due to
which the lower part of the potentiometer comes into picture. With a routine but
detailed analysis, it has been shown that duty cycle (

ʴ ) turns out to be:

1

ʴ ¼ 0

@

1
A

ð 15 : 54 Þ

k

2 R 2

k
1 k

ln

R p

ð 1 k Þ

1 k

1 þ

2 R 2
R p þk 1

ln

where k is the tuning factor of the potentiometer. Thus, the value of ʴ other than

50 % can be achieved by proper selection of the parameter k.

15.6.5 Chien ' s DO-DVCC-Based Square/Triangular Wave
Generator

A novel square/triangular waveform generator using single DO-DVCC and three
grounded passive components was advanced by Chien in [ 16 ] and is shown here in
Fig. 15.13
The operation of this circuit can be explained as follows. The Y 1 -Z + connection
along with the resistor R 2 forms the positive feedback path due to which the DVCC
saturates and hence, its output could be either in state V 0 or V 0 . In the on-duty cycle
period (T 1 ), V 01 is at positive saturation level in the beginning. In order this to
happen, the current I x must have a strong positive charge than I z . To accomplish this
R 2 needs to be larger than R 1 . Thus, capacitor C is charged, causing V 02 to be a
positive going ramp. The rate at which the capacitor charges linearly along with the
values of I x and I z are given by the following equations:

V 0 dV 02 t ðÞ

dt ¼

V 01
R 2 C ¼

V TH V TL

R 2 C ¼

ð 15 : 55 Þ

T 1

V 0 V 01 V 02 V 02

I X ¼ ¼ ð 15 : 56 Þ

R 1 R 1

V 0
R 2

V 01
R 2 ¼

I z ¼ I z 1 ¼ I z 2 ¼ ð : Þ

15 57

The positive ramp continues until V 02 reaches the upper threshold level (V TH )at
which time the output V 01 switches to low state V 0 . Now the capacitor voltage V 02
starts discharging linearly resulting in a negative going ramp at V 02 . During this
period, when the capacitor voltage crosses the lower threshold level (V TL ), the
circuit resumes the high state and this operation goes on repeating. The equations