Op Amps for Everyone - The Repeater Builder's Technical ...

Sine Wave Oscillator Circuits
R F
1.5 MΩ
R G
360 kΩ
+5 V
_
+
R
10 kΩ
+
_
2.5 V
10 nF
C
4/4 TLV2474
R
10 kΩ
R
10 kΩ
+
_
R
10 kΩ
+
_
V OUT
Sine
C
10 nF
C
10 nF C 10 nF
V OUT
Cosine
Figure 15–18.
Bubba Oscillator
V OUT = 1 V/div
Time = 500 µs/div
Figure 15–19. Output of the Circuit in Figure 15–18.
The gain, A, must equal 4 for oscillation to occur. The test circuit oscillated at 1.76 kHz
rather than the ideal frequency of 1.72 kHz when the gain was 4.17 rather than the ideal
gain 4. The output waveform is shown in Figure 15–19. Distortion is 1% for V OUTSINE and
0.1% for V OUTCOSINE . With low gain, A, and low bias current op amps, the gain setting
15-18