LM358, LM258, LM2904, LM2904V

6

MOTOROLA ANALOG IC DEVICE DATA

2

1

Vref =VCC

1

2

Figure 12. Function Generator

Figure 13. Multiple Feedback Bandpass Filter

For less than 10% error from operational amplifier.

If source impedance varies, filter may be preceded with voltage

follower buffer to stabilize filter parameters.

Where fo and BW are expressed in Hz.

Qo fo

BW

< 0.1

Given:

fo = center frequency

A(fo) = gain at center frequency

Choose value fo, C

Then:

R3 =

Q

π fo C

R3

R1 =

2 A(fo)

R1 R3

4Q2 R1 –R3

R2 =

+

–

+

–

–

+

Vref =VCC

Vref

f =

R1 + RC

4 CRf R1

R3 =

R2 R1

R2 + R1

R2

300 k

75 k

R3

R1

C

Triangle Wave

Output

Square

Wave

Output

VCC

R3

R1

R2

Vref

Vin

C

C

VO

CO

CO = 10 C

Rf

if,

1/2

LM358

Vref

1/2

LM358

1/2

LM358

100 k