2

2

2

2

2

1

1

1

1

1

1

R

C

A

R

C

R

C

R

C

Q

C

LP











Let R1=R2=R and C1=C2=C, the corner frequency and the pole quality factor can be simplified as below

CR

C

1





And

+

-

Figure 9. Sanllen-Key 2nd Order Active Low-Pass Filter

The 2

+

-

Figure 10. Sanllen-Key 2nd Order Active High-Pass Filter

2

1

2

1

1

1

1

1

2

2

1

1

1

1

2

2

)

(

)

(

R

R

C

C

R

C

HP

A

R

C

R

C

HP

IN

OUT

S

S

A

S

V

V

S













Where

SMD Type

OIC