LMV771 datasheet(21/34 Pages) TI

21 / 34 page

100

10k

100k

400k

FREQUENCY (Hz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

DC GAIN =

R5 + R6

R1 + R4

= -14.8 dB

Q =

R5 + R6

Zc =

C2R2

C2C3R2R3

C3R3

R5 + R6

R1 + R4

and

Q =

LMV771, LMV772, LMV774

www.ti.com

SNOSA04F – MAY 2004 – REVISED SEPTEMBER 2010

(26)

A design example is shown here:

Designing a bandpass filter with center frequency of 10kHz and Quality Factor of 5.5

To do this, first consider the Quality Factor. It is best to pick convenient values for the capacitors. C2 = C3 =

1000pF. Also, choose R1 = R4 = 30kΩ. Now values of R5 and R6 need to be calculated. With the chosen values

for the capacitors and resistors, Q reduces to:

(27)

R5 = 10R6 R6 = 1.5kΩ R5 = 15kΩ

(28)

Also, for f = 10kHz, the center frequency is

ωc = 2πf = 62.8kHz.

Using the expressions above, the appropriate resistor values will be R2 = R3 = 16kΩ.

The following graphs show the transfer function of each of the filters. The DC gain of this circuit is:

The frequency responses of each stage of the state variable active filter when implemented with the LMV774 are

shown in the following figures:

Figure 14. Lowpass Filter Frequency Response

Submit Documentation Feedback

Product Folder Links: LMV771 LMV772 LMV774

LMV771 Datasheet(PDF) 21 Page - Texas Instruments

LMV771 Datasheet(HTML) 21 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

Datasheet Download

Link URL