active load current amplifier

hi all
i need to design an active load current amplifier with output voltage 30V and output current at least 5 amp (rms).
please help me i am not experienced with current amplifier.

thanks alot.

I guess, you have additional specifications.

An important point is, if the load has to be ground referenced or can be floating, allowing a simple current sense resistor.

i think you mean i should use a kind of feedback amplifier?
could you help me with more detail of current amplifier or introduce me a source for learning about it?

thanks alot.

Can you please first tell the bandwidth range your dealing with? I was in fact considering a feedback amplifier which is the obvious solution in most cases, but not necessarily for your application. I don't know a literature specialized to current output amplifiers, I think, most design aspects a universal, valid for any kind of amplifier, e. g. loop gain, stability criterion, compensation.

hi

first i want to thank you for helping me.

the band width or the maximum input frequency that i want to have here is about 8Mhz
and the lower limit of input frequency is some hertz.so the range seems to be wide?

i appreciate if introduce me some source about current amplifier and also some practical circuit.

regard.

8 MHz signal BW is probably critical for overall feedback, but not excluding it completely. Alternatively stagewise internal feedback may be used. It can be expected to have lower linearity and gain (current) accuracy than overall feedback, but can achieve stability more easily. As the amplifier would most likely use a class AB mode, some crossover distortion can't be avoided. With internal feedback, it would appear in output current undiminished.

I want to ask a colleague, who made his PhD on current amplifiers about suitable literature. I probably met him within the next days.

Apart from bandwidth, the expectable load impedance range and the intended relative and absolute current accuracy are important parameters. With some types of load impedance, a ususal power OP with overall feedback can be an easy solution, I think.

the accuracy of amplifier is required to be normal. some error is acceptable.but not as much as it was unpredictable.

the load is some times unknown but it may change in range of some ohm (5 ohm to 10 or maybe 15).

i want to use this amplifier for long time (12 hours continously). i don't think that op is a good choice for this application.so what is you idea?

Power OP should be read as another word for standard VFB amplifier structure. I didn't consider a particular integrated or hybrid circuit. But if a matching device exists, why not using it?

Another question regarding load impedance. Resistive load promises easy compensation. How about series inductance or high frequency resonances?

hi

i think the load is a kind of inductive load.i mean series of resistive and inductive also let me describe about the load:

the load is kind of transformer with primary and secondary the secondary is open circuit.but we have also a frrite core just place inside coils. the primary connected to the amplifier so we want to study the effect of magentic field on the core.
the core is changed so the load is not constant.most of the power is dissipated in core because there is no lamination. so we have tow coil with some resistive and inductive load and a core. these are the load.
so what do you think about it?

I think, the load can be expected mostly inductive at frequencies that matter regarding stability. I asked the colleague, he said, he isn't aware of any specific current amplifier literature.

I'll think about the problem.

hi

thanks alot for helping. i will wait for your solution.

regard