OPA228 as oscillator

user3902491

Other Parts Discussed in Thread: OPA228

Hi,

I'm currently using OPA228 as sine wave oscillator (Wien-bridge) .
And here are several dumb problems that bugs me for a while.

1. There are some spikes on both positive and negative side of output wave.
Is it good to put small capacitor (12pF) between +VCC/-VCC and output in oscillator?

2. Is it okay leaving the trimming pins(1&8) disconnected? (output offset is already small enough)

3. Bandwidth of OPA228 is 33MHz according to datasheet.
Yet, heavy distortion occurs at 100kHz on my Wien-bridge oscillator.
Is this phenomenon normal? Or are there still some condition out of my concern?

Thank for any advice!

Kuo Jin-Yi

over 9 years ago

0 Hooman Hashemi over 9 years ago

TI__Mastermind 22825 points

Hi Kuo,

Is it possible for you to attach the schematic details?

Regards,

Hooman

0 user3902491 over 9 years ago in reply to Hooman Hashemi

Prodigy 30 points

Hi Hooman,

Of course!

Here's my schematic circuit.
R= 2.7kOhm, C = 5.6nF for 10kHz sine wave

and here's current output waveform

0 Hooman Hashemi over 9 years ago in reply to user3902491

TI__Mastermind 22825 points

Hi Kuo,

I'm sorry. I don't understand enough about how your oscillator functions to offer any help. I hope other people on the forum can jump in and help out.

Regards,

Hooman

0 user3902491 over 9 years ago in reply to Hooman Hashemi

Prodigy 30 points

Hi Hooman,

It's okay. Thanks for spending time on my question!

Hope you have a good day!

Kuo Jin-Yi

Amplifiers

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OPA228 as oscillator