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88.4 kΩ

18 pF

VCC+

VCC-

18 pF

18 pF

88.4 kΩ

88.4 kΩ

1N4148

1N4148

VCC-

VCC+

1 kΩ

- 15 V

6 cos ωt

15 V

18 kΩ

(see Note A)

1 kΩ

6 sin ωt

1/2

TL082

1/2

TL082

18 kΩ

(see Note A)

Output B

Output A

1.5 kΩ

VCC-

43 kΩ

220 pF

43 kΩ

VCC+

30 kΩ

VCC+

43 kΩ

VCC-

16 kΩ

43 kΩ

Input

220 pF

220 pF

16 kΩ

VCC-

VCC+

30 kΩ

VCC+

43 kΩ

220 pF

43 kΩ

VCC-

1.5 kΩ

1/2

TL082

2 kHz/div

Second-Order Bandpass Filter

fo = 100 kHz, Q = 30, GAIN = 4

2 kHz/div

Cascaded Bandpass Filter

fo = 100 kHz, Q = 69, GAIN = 16

Output A

Output

B

1/2

TL082

1/2

TL082

1/2

TL082

TL082-Q1

JFET-INPUT OPERATIONAL AMPLIFIER

SLOS548 – SEPTEMBER 2007

A.

These resistor values may be adjusted for a symmetrical output.

Figure 23. 100-kHz Quadrature Oscillator

Figure 24. Positive-Feedback Bandpass Filter

12

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