Recommend Opamp for integrator in audio oscillator

Hello, I am designing a 20hz to 20,000hz oscillator based on an implementation of a state variable sin and cosine generator.

Selection for opamp integrators has me scratching me head.

I'm currently torn between the AD744 and the AD845 . Budget constraints are placed a decent distance behind perfectionism.

The decompensated 744 has good speed which the perfectionist in me believes will translate to good sonics. All other specs seem good, though perhaps the 711 would be a safer choice.

The 845 seems to come recommended in the datasheet for this purpose, with what seems like a better output stage, although bias current is much higher.

Can any engineers help me with this choice? Any characteristics that I have neglected to observe (perhaps concerning phase response), or another (DIP) opamp to recommend? Or perhaps some recommended reading?

Many thanks in advance for any input.

Mark

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  • Hi Mark,

    Yes I agree,selection of op amp is not easy. You should be able to identify which parameters your application should be of most interest.It could be the noise, precision or the cost for example.  If your going to choose between AD845 and AD744, I would recommend AD744 where there are lots of good features compare to AD845. It is low power and has a good noise performance compare to AD845 too.I would also suggest that you simulate the device with spice model to verify the performance and suitability of the device in your application.

    Phil

Reply
  • Hi Mark,

    Yes I agree,selection of op amp is not easy. You should be able to identify which parameters your application should be of most interest.It could be the noise, precision or the cost for example.  If your going to choose between AD845 and AD744, I would recommend AD744 where there are lots of good features compare to AD845. It is low power and has a good noise performance compare to AD845 too.I would also suggest that you simulate the device with spice model to verify the performance and suitability of the device in your application.

    Phil

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