I want this for my project. So I have decided to make a basic Wien bridge oscillator.

$$f = \frac{1}{2\pi R C}$$

So if I choose a capacitor of 0.1 nano farads and a resistor of 10 ohms, I should get around 160 MHz. Will I get the 160 MHz, I heard that a wine bridge cancels out higher frequencies.

  • \$\begingroup\$ I'd forget the Wien bridge. (10 pF, 100 ohm.. but you still need gain of three(+)) For that type of frequency look into an LC and a transistor. \$\endgroup\$ – George Herold Sep 2 '14 at 22:00
  • \$\begingroup\$ why would you change values to 10pF and 100 ohm. \$\endgroup\$ – user124627 Sep 3 '14 at 3:11
  • \$\begingroup\$ 100Ω resistors are much more common than 10Ω. \$\endgroup\$ – duskwuff -inactive- Sep 3 '14 at 5:37
  • \$\begingroup\$ @user124627, You'll want to do this with an opamp? I figured the opmap will be happier with 100 ohms. It's an easier impedance for the opamp to drive. (less current requirement.) \$\endgroup\$ – George Herold Sep 3 '14 at 13:11

Selecting suitable parts values is ONE problem, which - however - could be solved in this case. The bigger problem is to find a suitable operational amplifier. A Wien-type oscillator needs a gain of three - and to achieve this (without disturbing phase shifts) for a frequency of 160 MHz requires an opamp with a gain-bandwidth product of at least several GHz. Therefore, I recommend to try one of the classical transistor-based oscillator topologies.

EDIT1: Another problem connected with the use of opamps is the limited slew rate of these devices - even if you could find an opamp with the required gan-bandwidth product.

**EDIT2:**There are some special opamp topologies which can be used for an 160MHz Wien oscillator: Current-feedback amplifiers exhibit very large gain-bandwidth products and phantastic slew rates (SR). Example: OPA695 allows a gain of three at 160MHz with a slew rate SR=4300V/µs.

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  • \$\begingroup\$ thankyou so much, I didn't know op amps have bandwidth \$\endgroup\$ – user124627 Sep 7 '14 at 18:57
  • \$\begingroup\$ hey, won't a 741 op amp work \$\endgroup\$ – user124627 Sep 7 '14 at 18:58
  • \$\begingroup\$ would 3volts be enough Vcc for OPA695 \$\endgroup\$ – user124627 Sep 7 '14 at 18:59
  • \$\begingroup\$ A 741 type certainly will NOT work for this purpose. Regarding supply voltages for the OPA695: Why didn´t you consult the data sheet? \$\endgroup\$ – LvW Sep 8 '14 at 8:55

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