INT- why Bubba oscillator does not work?

Hawk Tong

Other Parts Discussed in Thread: TLV2474, OPA365, TLC555

6332.OpAmp_Oscilitor_slyt164[1].pdf.pdfDear all,

I try to simulate a Bubba oscillator in TI-TINA. it is strange that the circuit does not work. i don't know why. wish for your suggestions. thanks in advance.

For details, pls refer the attached file. and rename the file as .tsc.

3771.Bubba oscillator-TSC.pdf

thanks your help in advance.

Hawk Tong

over 13 years ago

0 Rick Downs - WEBENCH Design Center over 13 years ago

TI__Expert 5515 points

Hawk,

Sometimes getting oscillator circuits to simulate is tricky, because oscillators often rely on inherent noise and such to start the oscillation (and those things may not be modeled in the macromodels of the op amps, at least not enough to cause the simulation to replicate reality!). I notice too that you're using OPA365 instead of the TLV2474, and it could be that differences in the GBW of the amplifiers may require different gain to sustain oscillation.

I'll look into this for you, but may take a day or two.

0 Rick Downs - WEBENCH Design Center over 13 years ago in reply to Rick Downs - WEBENCH Design Center

TI__Expert 5515 points

Simplest solution to getting it to simulate: change the Integration method (in the Transient Analysis dialog box) to Trapezoidal instead of Gear. This shows the sustained oscillations (suggested by Simulating Oscillators Using SPICE [requires IEEE password]). Worked for me.

0 Neil Albaugh over 13 years ago in reply to Rick Downs - WEBENCH Design Center

Genius 5430 points

Rick;

This is a common problem with oscillators and timers such as a TLC555. To get the oscillation started, simply set the TINA transient analysis "initial condition to zero"; if it is set to "calculate operating point", it does that and then just sits there.

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INT- why Bubba oscillator does not work?