ADA4665-2

Rev. 0 | Page 16 of

20

ADA4665-2

1/2

R1

22.5kΩ

R2

22.5kΩ

C1

1nF

C2

0.5nF

Figure 57. Two-Pole Low-Pass Filter

When R1 = R2 and C1 = 2C2, the values of Q and the cutoff

frequency are calculated as follows:

)

(

R2

R1

C2

+

C2

C1

R2

R1

Q =

2

R1 R2 C1 C

f

c

π

=

2

1

10

0

–10

–20

–30

–40

–50

–60

100

1k

10k

100k

1M

FREQUENCY (Hz)

Figure 58. Low-Pass Filter: Gain vs. Frequency

Figure 59 shows a two-pole high-pass filter, with cutoff frequency

at 10 kHz and quality factor, Q, of 1/√2.

ADA4665-2

1/2

R1

22.5kΩ

R2

45kΩ

C1

0.5nF

C2

0.5nF

Figure 59. Two-Pole High-Pass Filter

When R2 = 2R1 and C1 = C2, the values of Q and the cutoff

frequency are calculated as follows:

)

(

C2

C1

R1

C2

C1

R2

R1

Q

+

=

C2

C1

R2

R1

f

c

π

=

2

1

0

–10

10

–20

–30

–40

–50

–60

–70

–80

–90

–100

–110

–120

10

100

1k

10k

100k

1M

FREQUENCY (Hz)

Figure 60. High-Pass Filter: Gain vs. Frequency