Application Notes (Continued)
10006039
FIGURE 15. State Variable Active Filter
A design example for a bandpass filter is shown below:
Assume the system design requires a bandpass filter with f O
= 1kHz and Q = 50. What needs to be calculated are
capacitor and resistor values.
First choose convenient values for C1, R1 and R2:
C1 = 1200pF
2R2 = R1 = 30kΩ
Then from Equation (11),
From Equation (12),
where for all three filters,
(11)
(12)
From the above calculated values, the midband gain is H 0
R3/R2 = 100 (40dB). The nearest 5% standard values have
been added to Figure 15.
=
4.5 PULSE GENERATORS AND OSCILLATORS
A pulse generator is shown in Figure 16. Two diodes have
been used to separate the charge and discharge paths to
capacitor C.
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