I am trying to generate a sine wave signal. I am following this guide http://www.ti.com/lit/ml/sloa087/sloa087.pdf from TI. The thing is I cannot find the IC that they are using (TLV2471) and I only have OPA604 and LM3900 op-amp and the circuit doesn't work. I have tried the Wien Bridge from page 12 and phase shift oscillator from page 17.

For the Wien Bridge circuit, the OPA604 give very small amplitude sine wave (from about 2.3 to 2.7V) and the frequency reading in my oscilloscope jungling around from 50kHz to 40Mhz. the LM3900 give a nearly square wave at about 5kHz.

For the phase shift oscillator circuit, the OPA604 gives a similar small sine wave with jumping frequency while the LM3900 gives no oscillation, the ouput just stay at about 2.5V.

So could anyone please help. Any pointing is also greatly appreciated.


1 Answer 1


Your OPA604 needs at least a 9v supply and even then it doesn't have the 'rail-to-rail' outputs of the TLV2471.
Your circuit might still work work this opamp if you increase the supply voltage though.

The LM3900 is not a 'normal' opamp. Its a Norton type which works on the currents into/out of its inputs and not the voltages on them.
This one will never work in that circuit.

  • \$\begingroup\$ I am trying to get a few more op-amp, including LM4136, LMC660, LM386. Is any of them will work with these circuits? \$\endgroup\$
    – mihota
    Dec 4, 2014 at 18:48
  • 1
    \$\begingroup\$ The LM386 isn't an opamp at all. \$\endgroup\$
    – user16324
    Dec 4, 2014 at 19:19
  • \$\begingroup\$ The LM4136 will probably give you much the same result as your OPA604 for the same reasons. You'll probably have more success with the LMC660 as its specs are a lot closer to the TLV2471 (at least as far as your circuit is concerned). And as Brian's already said, the LM386 is definitely not an opamp. \$\endgroup\$
    – brhans
    Dec 4, 2014 at 20:05
  • \$\begingroup\$ I think, you can, of course, realize an oscillator based on the OPA 604. Question: Why do you think that an amplitude of app. 2.5 volts is "very small"? It would be wise if you could show us your circuit. I recommend to stay with the WIEN topology - it is very easy to design. What is the desired frequency? Do you know what "amplitude control" means? Do you know the meaning of Vref in the figure within the document ? Are you working with single or double supply? \$\endgroup\$
    – LvW
    Dec 4, 2014 at 20:13
  • \$\begingroup\$ @LvW sorry for being not clear. What I mean is the sine output is from 2.3 to 2.7V, so the amplitude is about 0.4V. In the end I want a frequency from about 10kHz to 100kHz, and it doesn't need to be changable. I don't really understand "amplitude control" and the meaning of Vref. And I am working with double supply, but I want to change to single supply. \$\endgroup\$
    – mihota
    Dec 5, 2014 at 3:01

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