AD8515AKS Analog Devices, AD8515AKS Datasheet - Page 13

• Manufacturer Part Number: AD8515AKS
• Description: 1.8 V Low Power CMOS Rail-to-rail Input/output Single Operational Amp
• Manufacturer: Analog Devices

Wien Bridge Oscillator
The circuit in Figure 7 can be used to generate a sine wave, one
of the most fundamental waveforms. Known as a Wien Bridge
oscillator, it has the advantage of requiring only one low power
amplifier. This is an important consideration, especially for battery-
operated applications where power consumption is a critical
issue. To keep the equations simple, the resistor and capacitor
values used are kept equal. For the oscillation to happen, two
conditions have to be met. First, there should be a zero phase
shift from the input to the output, which will happen at the
oscillation frequency of
Second, at this frequency, the ratio of VOUT to the voltage at
+input (Pin 3) has to be 3, which means that the ratio of
R11/R12 should be greater than 2.
REV. B
Figure 7. Low Power Wien Bridge Oscillator
1nF
C10
F
OSC
R13
1k
=
2
R12
1k
p
R
3
2
10
1nF
C9
1
¥
VCC
VEE
2.05k
V+
V–
R11
C
U10
10
AD8515
R10
1k
1
–13–
High frequency oscillators can be built with the AD8515 due to its
wide bandwidth. Using the values shown, an oscillation frequency of
130 kHz is created and is shown in Figure 8. If R11 is too low, the
oscillation might converge; if too large, the oscillation will diverge
until the output clips (V
Figure 8. Output of Wien Bridge Oscillator
0
0
0
0
0
0
0
0
0
0
0
0
S
0
= ± 2.5 V, F
TIME (2 s/DIV)
0
0
OSC
0
= 130 kHz).
0
0
AD8515
0
0