AC signal current amplifier circuit

Shrikant Lokhande

Other Parts Discussed in Thread: OPA547, BUF634

Hello all,

I have designed a function generator which gives me 12Vpp(max) sine wave output.

I need to design AC amplifier with both voltage and current gain, AC output I require is 24Vpp @ 80mA max.

I was thinking of using a transistor based amplifier but I may not get the current amplification I required (please correct me if I'm wrong).

Please suggest me the circuit which will give me both AC current and voltage gain.

Thanks and regards,

Shrikant

over 14 years ago

0 Bruce Trump over 14 years ago

Guru 21975 points

Shrikant,

Have you considered a power op amp such as the OPA547? Or, the BUF634 can be added inside the feedback loop of a conventional op amp. Both approaches would appear to meet your requirements.

Regards, Bruce.

0 Shrikant Lokhande over 14 years ago in reply to Bruce Trump

Intellectual 655 points

Hi Bruce ,

Thanks for the reply, I read few other TI E2E threads as well.

Some of the specifications of my design are:

My load is reactive load like a coil which I need to give 80mA current for the stronger magnetic field.

I have been simulating hall effect sensors using this magnetic field.

I have tested this using function generator which was working fine, but I want to design sine wave by my own.

My designed sine wave is 12Vpp w.r.t GND, but the sourcing current is very low which I need to amplify.

Will this amplifier be used directly for reactive loads?

Suggestions are welcome!!

Regards

Shrikant.

0 Bruce Trump over 14 years ago in reply to Shrikant Lokhande

Guru 21975 points

Shrikant,

Yes, the OPA547 or BUF634 can be used to drive an inductive load. If the output of your present circuit is an op amp, you may be able to boost its output current by adding the BUF634 inside the feedback loop. Check the BUF634 data sheet for details on how this is done.

Regards, Bruce.

0 Shrikant Lokhande over 13 years ago in reply to Bruce Trump

Intellectual 655 points

Hi Bruce,

While testing OPA547 with input 12Vpp ( 1 - 10kHz ) in unity gain non inverting configuration the output seems to be perfect but when tested with G = 2, the output waveform seemed clipped in the positive half cycle.

Supply given to the OPA547 is + and - 22V.

What could be the reason for this.

Thanks and regards,

Shrikant

0 Bruce Trump over 13 years ago in reply to Shrikant Lokhande

Guru 21975 points

Shrikant,

Can you please provide a circuit diagram and scope photo of the behavior in G=2?

Please do not submit the same question twice. I will delete your first posting.

Regards, Bruce.

0 Shrikant Lokhande over 13 years ago in reply to Bruce Trump

Intellectual 655 points

Hi Bruce,

The circuit diagram for G=2 configuration is as follows:

The output waveform for this circuit is as follow:

Input waveform is as shown here:

thanks and regards,

Shrikant.

0 Shrikant Lokhande over 13 years ago in reply to Shrikant Lokhande

Intellectual 655 points

Sorry Bruce,

I'm trying to insert the waveforms but It is not displayed in the post.

thanks and regards,

Shrikant.

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AC signal current amplifier circuit