Realization of Sinusoidal Oscillators Using CCs - Current Conveyors: Variants, Applications and Hardware Implementations - page 200

a b

y

V 0

z

CCII+

T 1 (s)

x

C 3

R 3

y

x

T(s)

y

V 1

2

y CCII+ z z

CCII+

V 2

x

C 2 R 2

x
R 1

C 1

c

Fig. 7.13 Quadrature oscillator proposed by Horng (Adapted from [ 44 ] 2005 Elsevier) (a) The

circuit configuration (b) Experimental result (c) Variation of oscillation frequency with respect to
R 1

©

sub-harmonically pumped frequency conversion circuits. A number of quadrature
and multi-phase oscillator topologies using CCs have been reported in literature, for
example, [ 21 , 23 , 27 , 33 , 34 , 44 , 45 , 48 , 49 , 52 ]. In the following, we discuss a
number of quadrature and multi-phase oscillators.
Quadrature oscillators are circuits which provide two sinusoidal signals having
90 phase difference. In the literature there has been lot of efforts on making
quadrature oscillators out of which the designs based upon all pass filters are
quite common. One such circuit proposed by Horng [ 44 ] is shown in Fig. 7.13 .
The condition of oscillation and oscillation frequency are given by:

r

1
C 2 C 3 R 1 R 3

C 1 R 2 ¼ C 3 R 3 ; ω o ¼ ð 7 : 32 Þ