OPA189: Simulation of VCO using OPA189

gary mella

Part Number: OPA189

I am trying to simulate VCO circuit using OPA189 in TINA with no success Could you help in resolving the problemVCO_Test.TSC

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

And what IS the problem?

Kai

0 gary mella over 5 years ago in reply to kai klaas69

Intellectual 440 points

Simulation output should be frequency and the circuit shows a DC value

0 kai klaas69 over 5 years ago in reply to gary mella

Guru 140200 points

Hi Gary,

because the -input of OPAmp sits on virtual ground, T1 has no effect when being turned-on or turned-off. This circuit cannot work. Where do you have this circuit from?

Kai

0 Tamara M Alani over 5 years ago

TI__Genius 10850 points

Hi Gary,

Thank you for your post. Many of us are on holiday break, so we will support you shortly.

-Tamara

0 Raymond Zhang1 over 5 years ago in reply to Tamara M Alani

TI__Guru 57611 points

Hi Gary,

Enclosed is an example of VCO with OPA189. If you have questions, please let us know.

Regards,

Raymond

VCO 12302019.TSC

0 gary mella over 5 years ago in reply to Raymond Zhang1

Intellectual 440 points

Hi Raymond,

Can it be made to work for bioplar DC voltage inputs?

0 kai klaas69 over 5 years ago in reply to gary mella

Guru 140200 points

Hi Gary,

you can shift the bipolar input signal and by this convert it into an unipolar signal which is needed by the circuit.

Can you tell more about your application? Why is a bipolar control input voltage needed? What shall be the effect of a negative control input voltage?

Kai

0 gary mella over 5 years ago in reply to kai klaas69

Intellectual 440 points

ok, it was a curious question. BTW, when we increase the simulation time to 1s, I get convergence error in TINA. Could you resolve the problem.

0 kai klaas69 over 5 years ago in reply to gary mella

Guru 140200 points

Hi Gary,

change the analysis parameters. This works for me:

Kai

0 gary mella over 5 years ago in reply to kai klaas69

Intellectual 440 points

Can you explain what they mean? And I am also interested to get the same frequency for -2V as well. Purpose is academic

0 kai klaas69 over 5 years ago in reply to gary mella

Guru 140200 points

Hi Gary,

the TINA related questions you might better directly address to TINA itself:

If you want to get the same frequency for a control voltage of -2V and +2V, I would recommend to insert a double wave rectifier built with two OPAmps.

Kai

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OPA189: Simulation of VCO using OPA189