AD8027/AD8028

Rev. B | Page 21 of 24

Band-Pass Filter

In communication systems, active filters are used extensively in

signal processing. The AD8027/AD8028 is an excellent choice

for active filter applications. In realizing this filter, it is impor-

tant that the amplifier has a large signal bandwidth of at least

in the amplifier, causing instability and oscillations.

In the schematic shown in Figure 62, the AD8027/AD8028 is

configured as a 1 MHz band-pass filter. The target specifications

the equations shown below, calculate the remaining variables.

The test data shown in Figure 63 indicates that this design

a bandwidth of 450 kHz.

(MHz)

(MHz)

Band

Pass

f

Q

O

=

C2 = 0.5C1

R1 = 2/k, R2 = 2/(3k), R3 = 4/k

H = 1/3(6.5 – 1/Q)

R5 = R4/(H – 1)

+5

–5

C3

0.1

µF

C4

0.1

µF

R4

523

Ω

R5

523

Ω

C2

500pF

C1

1000pF

R3

634

Ω

R1

316

Ω

R2

105

Ω

SELECT

AD8027/

AD8028

+

–

03327-A-061

Figure 62. Band-Pass Filter Schematic

0.1

CH1 S21 LOG

5dB/REF 6.342dB

1:6.3348dB 1.00 000MHz

1

FREQUENCY – MHz

10

1

03327-A-062

Figure 63. Band-Pass Filter Response

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