Electric Circuits and Networks, Ist Edition by Pearson

‘Constant-k’ implies that the product of underlying impedances Z

1

and Z

2

must be a

constant independent of frequency.

Therefore, L

1

C

1

has to be equal to L

2

C

2

if the filter is to be of a constant-k type. This

constraint is imposed on band-pass filter design.

∴=

=

LC LC

L

C

11 2 2

2

1

by design.

Then, Z Z

This product is define

12

dd as of the filter.

o

o

R

RZZ

L

C

L

C

LC LC

2

12

2

1

1

2

11 2 2

∴= = = =()∵

ZjL

jC

j

LC

C

ZjL

jC

j

L

LC

11

1

2

11

1

22

2

2

2

22

1

1

1

1

=+ =−

−

()

==

−

()

ω

ω

ω

ω

ω

ω

ω

ω

//

∴∴=

−

()

×

−

()

=×

−

()

−

ZZ

LC

C

L

LC

L

C

LC

LC

12

2

11

1

2

2

22

2

1

2

11

2

22

1

1

1

1

ω

ω

ω

ω

ω

ω

(()

725

16.14 CONSTANT-k BAND-PASS FILTER

16.14 CONSTANT-k BAND-PASS FILTER

Constant-k T-section and Π-section band-pass filters are shown in Fig. 16.14-1.

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