# Bubba oscillator with TLV2474

Posted on Feb 5, 2014

understanding of the function and sizing of the resistors Rg and Rf for the bubba oscillator circuit described on the application report SLOA060 - march 2011, page 17 figure 18. The oscillator porpuse is to develope a current inverter thru the H-bridge topology, oscillating on a frequency of 60Hz. The RC filter i`ve calculated from the equation

`f=(1/(2*pi*R*Cs)` in order to oscillate on this particular frequency is built up by either a 26, 5kOhm resistor and 100nF capacitor or a 3, 9kOhm resistor and 680nF capacitor, for all four RC filters. The op amp i am going to use for this circuit is the same presented by the application note, TLV2474. I`d apreciate very much if you could help me with this and even tell me if this circuit is able to fulfill the task. Thank you very much in advance! Getting an oscillator to start up in a PSpice simulator can sometimes be a little tricky because the simulation circuitsometimes need a bit of pushortheright start-up conditions to get it going. However, TINA-TI is usually pretty good about doing so - at least from my experience. The way to get the Bubba oscillatorstartedfor this case is to selectthe Analysis tab, andTransient. Then, when the Transient Analysis window appears, move the bullet selection from Calculate operating point, to either Use initial conditions, or Zero initial values. Once the simulation is completed the transient analysis should display the oscillation at the designated measurement points. You can see the results I obtained: The point of oscillation in the Bubba occurs when the phase shift of each of the four stages is -45 degrees. The unadjusted gainat -45 degrees phase shift is -3 dB, or 0. 707 V/V. If each stage has a gain of 0. 707 V/V, then the overall gain would be (0. 707)4 or 0. 25 V/V. Therefore,...

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