AD8515ARTZ Analog Devices, AD8515ARTZ Datasheet - Page 15

• Manufacturer Part Number: AD8515ARTZ
• Manufacturer: Analog Devices

WIEN BRIDGE OSCILLATOR
The circuit in Figure 38 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 happens at the oscillation frequency of
Second, at this frequency, the ratio of VOUT to the voltage at the
positive input (+IN, Pin 3) has to be 3, which means that the
ratio of R11:R12 should be greater than 2.
f
OSC
=
C10
1nF
2
π
Figure 38. Low Power Wien Bridge Oscillator
R10
1
×
C10
R13
1kΩ
R12
1kΩ
3
2
1nF
C9
+
–
V+
V–
VEE
VCC
U10
2.05kΩ
AD8515
1kΩ
R19
R11
1
Rev. D | Page 15 of 16
High frequency oscillators can be built with the AD8515,
due to its wide bandwidth. Using the values shown, an oscilla-
tion frequency of 130 kHz is created and is shown in Figure 39.
If R11 is too low, the oscillation might converge; if too large,
the oscillation diverges until the output clips (V
f
OSC
= 130 kHz).
Figure 39. Output of Wien Bridge Oscillator
S
= ±2.5 V,
AD8515