Handbook for Sound Engineers

714 Chapter 20

(20-17)

from which it is found that

(20-18)

By choosing for C a value of 0.02PF, Eq. 20-18
yields a value for R of 15.9 k:.

Taking Fig. 20-16C for the second-order section

along with its transfer function leads to the

identification

(20-19)

and

Figure 20-16. Active high-pass, low-pass, and band-pass filter.

A. First-order unity gain low-pass. B. First-order unity gain high-pass.

E. Modification of operational amplifier required

to produce a pass band gain of K (K –1) in A through D.

D. Second-order unity gain high-pass.

BPF = Unity gain

bandpass filter

F. Second-order, two-pole pair noninverting bandpass filter.

G. Inverting band reject filter with adjustable notch depth.

C. Second-order unity gain low-pass.

BPF

+

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+

• 
  

+

• 
  

+

• 
  

+

• 
  
  
  
  • 
    
    
    
    • 
      
    
    
    
    
  
  
  
  

+

• 
  

R

C

C

R

R 1 R 2

R 1 R^2

RB

RA R^1

R 1 R^2

RB RA

R

RV

R

R

RV ¾R

C 1 C 2

C 1 C 2

C

C

Vi Vi

Vi Vi

Vi

Vi

Vo

Vo

Vo

Vo Vo

Vo Vo

K – 1 =

RA

RB

Z 0

S+Z 0

---------------

1

RC

--------

S^1

RC

--------+

= -----------------

Z 0 1

RC

--------=

= 2 Sf 0

= 2 S500 Hz.

Z 02

S^2 ++SZ 0 Z 02

-------------------------------------

1

R 1 R 2 C 1 C 2

--------------------------

S^2

R 1 C 2 +R 2 C 2

R 1 R 2 C 1 C 2

©¹§·--------------------------------S^1

R 1 R 2 C 1 C 2

++--------------------------

=-------------------------------------------------------------------------------------

Z 0 1

R 1 R 2 C 1 C 2

=------------------------------

= 2 S500 Hz