LMV822-N: Sine wave generate

Hello Kevin,

The example uses a 130MHz (130V/us) op amp to generate a 1 MHz sine. A fast op amp is needed for the oscillator to run at the desired frequency and slew fast enough to support the edges. A comparator would work better here, but that requires another IC. A fast op amp is needed to support a dual pole low pass filter. 

To get a different output frequency but have the same performance you could pick an op amp that has a bandwidth that is 130 times the desired output frequency. However something a little slower should also work. 

Hi Kevin,

I also recommend taking a look at AN-31 amplifier circuit collection for other possible solutions for a sine wave generator. Figure 23 and Figure 24 provides a low cost simple sine wave generator solution. You can also click on the "schematic" hyperlink in the document to open up a TINA  simulation file of the circuit in the figure to run a simulation of the circuit.

Thank you,

Tim Claycomb

Hi Kevin,

This thread already has some good answers, but I just wanted to add my $0.02.

I recently spent some time going through some of the existing TI content on sine wave generators with op amps and I found the following circuit to work the best.

By "the best," I mean the buffered-phase shift oscillator gave me the most accurate results such that my expected operating frequency and simulated operating frequency came closest with the help of this circuit.  You can read more about it in section 8.3 of our Sine Wave Oscillator application note or pages 35 and 36 of this journal article.  Note that the theory for this circuit is like that of the phase shift oscillator.  But the buffered version gives us more predictable results at the cost of more amplifiers.

As Ron has alluded too, you will need to pick an amplifier that is sufficiently fast.  I found that a good rule of thumb is that the bandwidth of the part should be about 100x the operating frequency of the sine wave generator.  Lastly, the circuit you found in the app note you've linked may work for your application.  However, I found that the expected and simulated operating frequencies were not as similar as I would have liked.

I recommend you build your circuit in TINA-TI and simulate it as this will allow you to fine-tune your component values.

Regards,

Daniel

Hi Kevin,

what frequency are we talking about? What about distortion? What about amplitude stability? What about frequency stability? Must the frequency be tunable? And and and... So, please give us more details.

Kai

Dear All,

Thanks for the comments.

Customer would like to generate 3.3V and 60Hz reference sine wave for the inverter.

The power on the board is 12V, so they expect 12V can generate 3.3V and 60Hz directly

They are also evaluating the XR2206, since it seems more easier.

Hope the guru here can give me more ideas about how to generate 3.3V and 60Hz by 12V input.

Appreciated!

BR

Kevin

Dear Ron,

Thanks for the input.

Is it possible can get the 0~3.3V sine wave?

Since the customer will need 0~3.3V for reference

BR

Kevin

The good old phase shift oscillator offers another option that might be useful:

https://www.planetanalog.com/when-an-input-is-an-output/

Kevin,

This is close to 0V to 3.3V 

60Hz Osc DC.TSC