LS404 查看數據表（PDF） - STMicroelectronics

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LS404

HIGH PERFORMANCE QUAD OPERATIONAL AMPLIFIER

STMicroelectronics 

LS404

In the circuit of figure 14, for fc = 3.4kHz and Ri =

R1 = R2 = R3 = 10kΩ, we obtain:

Ci = 1.354 R-1-- 2----π-1---f--c-- = 6.33nF

C1 = 0.421 R-1-- 2----π-1---f--c-- = 1.97nF

C2 = 1.753 R-1-- 2----π-1---f--c-- = 8.20nF

C3 = 0.309 R-1-- 2----π-1---f--c-- = 1.45nF

C4 = 3.325 R-1-- -2---π-1---f--c- = 15.14nF

The same method, referring to table 2 and figure

15 is used to design high-pass filter. In this case

the damping factor is found by taking the recipro-

cal of the numbers in table 2. For fc = 5kHz and Ci

= C1 = C2 = C3 = 1nF we obtain:

Ri = 0----.-3-1---5---4-- C-1-- -2---π-1---f--c-- = 25.5k Ω

R1 = 0----.-4-1---2---1-- C-1-- -2---π-1---f--c-- = 75.6kΩ

R2 = 1----.-7-1---5---3-- C-1-- -2---π-1---f--c-- = 18.2kΩ

R3 = 0----.-3-1---0---9-- C-1-- -2---π-1---f--c- = 103kΩ

The attenuation of the filter is 30dB at 6.8kHz and

better than 60dB at 15kHz.

Table 2 : Damping Factor for Low-pass Butterworth Filters

R4 = 3----.-3-1---2---5-- C-1-- -2---π-1---f--c-- = 9.6kΩ

Order

2

3

4

5

6

7

8

Ci

1.392

1.354

1.336

C1

0.707

0.202

0.92

0.421

0.966

0.488

0.98

C2

1.41

3.54

1.08

1.75

1.035

1.53

1.02

C3

0.38

0.309

0.707

0.623

0.83

C4

2.61

3.235

1.414

1.604

1.20

C5

0.259

0.222

0.556

C6

3.86

4.49

1.80

C7

C8

0.195

5.125

Figure 15 : 5th Order High-pass Filter (Butterworth) with Unity Gain configuration

R2

Ci

C1

C2

Ri

R1

R4

C3

C4

R3

8/11

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