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Help needed with amplifier design.

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poodina

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I am generating a sine wave using a micro-controller and resistive ladder,freq of 100Hz-800Khz. it is than shifted to 0v origin using level shifter circuit, and amplified to 5V peak to peak.
I need this 5Vpp signal to amplified to 70vpp-90Vpp, using a suitable voltage amplifier, do I use a single stage amplifier to do this or a 2 stage, like the first one amplifies to 30Vpp a filter stage in between and than a second stage to take it to 70vpp or 90vpp. What sort of amplifier should be used class A or Class AB.
dual supply voltage of +/-50V can be provided using a SMPS , the output voltage swing is needed more than the power [current]. the load is a 8Ohm coil.Any circuit or theory will help.
Please advise. Thank you.
 

FvM

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Good audio power amplifiers are able to achieve the intended bandwidth, at least after adjusting the frequency compensation. Many examples have been posted a edaboard before. If low distortion isn't an objective, a more simple circuit may be sufficient. Class AB should be preferred in any case.

A "coil" can be expected rather as an inductive than resistive load, I think.
 

muthukumar_ece2004

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Best to use Inductive based two stage amplifier. First stage could be used as pre-amplifier for boosting voltage level and second stage with low gain and high current booster amplifier. An inductive based amplifier only helps to abrupt amplification of input signal.
 

FvM

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Best to use Inductive based two stage amplifier.
Don't know what you exactly mean with "inductive based". The requirement is wideband operation 100Hz-800Khz.
 

poodina

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The 100Hz to 800 Khz is the frequency generated using a controller, it's for an experiment I need to perform, so I need to generate frequency from100Hz to 800Khz. The load is a single turn copper coil, with a 8ohm resistance in series this can be changed for impedance matching, but right now ,I have being doing my experiment with 8 ohm resistor.

I need more voltage in the coil, that what I need to achieve to proceed further.
The sine way should be distortion free as it will be picked up by a matching receiver and compared to the generated wave later.
Any good amplifier circuit available will help.
 

poodina

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90 V p-p ~ 32V rms / 8 = 4A X 32 = 128W!!!! You will need a very good FET Hi Fi amp that you are going to have to tweak to maintain its loop gain at 800KHz.
Frank
Frank , That's why I need help with theory of a good amplifier. And hence the choice of a Class AB amplifier for the experiment.Any help with design of the amplifier [class AB] over the frequency range would help.
 

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