Analog Filter Design Revisited: Circuit Configurations Using Newer Varieties of CCs - Current Conveyors: Variants, Applications and Hardware Implementations - page 368

(b) if we select V i1 ¼ V i2 ¼ Vin and V i3 ¼ 0, an APF can be realized at V 03 i.e.

n

R 3 R 1 R 2

o

s 2 C 1 C 2

1 1 1

R 1 R 2 R 3

sC 2 þ

V 03
V in ¼

ð 12 : 18 Þ

Ds ðÞ

Case II
From equations ( 12.12 ) and ( 12.13 ), the following filter responses can be obtained
by proper selection(s) of input signal(s): LPF: V i3 ¼ 0, V i1 ¼ V in ,orV i2 ¼ V in and

V out ¼ V 02 ; BPF: V i1 ¼ V i3 ¼ 0, V i2 ¼ V in and V out ¼ V 03 ; HPF: V i1 ¼ V i2 ¼ 0,

V i3 ¼ V in and V out ¼ V 03 ; Notch: V i2 ¼ V i3 ¼ 0, V i1 ¼ V in and V out ¼ V 03 ; APF:

V i3 ¼ 0, V i1 ¼ V i2 ¼ V in , and V out ¼

V 03

The angular frequency ( ˉ 0 ) and quality factor (Q 0 ) of all the filter responses is

given by:

r

1
C 1 C 2 R 1 R 2

ω 0 ¼ and ð 12 : 19 Þ

R 1 R 2 C 1
C 2

r

1
R 3

Q 0 ¼ ð 12 : 20 Þ

Thus, ˉ 0 and Q 0 can be controlled by R 1 and /or R 2 and R 3 , in that order.

Tsukutani-Sumi-Yabuki biquad Figure 12.6 shows a CM biquad filter structure
employing two plus type DO-DVCCs and grounded passive elements. The config-
uration is capable of realizing LPF, BPF, HPF, notch and APF fitter responses by
proper selection of input and output terminals. The filter parameters ˉ 0 and Q 0 are

orthogonally controllable. Since all passive elements are grounded, the configura-
tion is attractive for IC implementation in both bipolar and CMOS technologies.

I in1

y 2 z+

DVCC
z+

C 1

y 1

x

I 01

R 1

I in2

y 2

z+

DVCC
z+

y 1

x

C 2

I 02

R 2

Fig. 12.6 CM biquadratic
filter proposed by Tsukutani
et al. [ 7 ]