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INA103: Need help in designing customized amplifier (Request for reference design)

Faiz Majeed
Prodigy 115 points
Part Number: INA103


Tool/software:

Hi,

I am designing an amplifier which get input of 0 to 20V (peak voltage can varry from 2V to 20V) with 2 to 3 MHZ frequency. I want to amplify the input signal to gain of 7.5. so the maximum output on 20V need to be 150 V. 
is there any specific amplifier I can use form texas instruments ? Considering output current need to be 500mA.
I tried searching it by applying different filters but I am unable to do it. 

thank you

  • 0
    TI__Genius 15356 points

    Hi Faiz,

    The highest supply power amplifier goes to 180V, but will only be able to drive about 40-45mA of output current. 

    The best solution here would likely be to use an external class AB output stage with power transistors. This transistor drive could be used with a HV amplifier or a power amplifier. 

    The real problem however would be the need for speed. 3MHz sine wave at 150Vpp equates to something like 1500V/us slew rate. I do not know if this will be achievable without using a very fast drive amp and very fast transistors.

    Is the input signal purely sinusoidal? 

    Do you care about DC accuracy?

    In short, we certainly do not have a one chip solution, but it may be possible to realize this depending on application requirements. 

    Thanks,

    Jacob

  • 0 in reply to Jacob Nogaj
    Prodigy 115 points

    Thank you for your response.

    Would it simplify the design if the input signal were a square wave instead of a sine wave? In that case, could a solution based on MOSFETs work more effectively?

    I am particularly interested in exploring solutions using Texas Instruments components due to the excellent documentation and support provided. Could you kindly share references, recommended components, or application notes that might help guide me in designing this circuit?

    Additionally, I’d appreciate any insights on achieving the required slew rate and output power under these revised conditions.

    Edit: Also if we compromise the DC accuracy, can we amplify to lower voltage and then use high speed tranformer to step up more. 

    Thank you again for your guidance!

  • 0 in reply to Faiz Majeed
    TI__Genius 15356 points

    Hey Faiz,

    Thank you for the kind words regarding TI. We are happy to help you achieve your design goals!

    Yes, a square wave would be a bit easier to realize, but it is important to recognize that this will still be challenging to realize. 

    It is possible to use a transformer to do some of what we are talking about, but remember this transformer would be challenging to implement for the speed and power required for this application. 

    The closest reference design to what you are creating would likely be a traction inverter: https://www.ti.com/tool/TIDM-02014

    The problem is that these inverters are not going nearly as fast as the input signal you are trying to use. 

    What is the end equipment this is going in? This may help me find reference designs if they exist for similar products. 

    Using an external IGBT/FET based output stage with a gate driver may be the easiest way to get this working. Lets say we use the square/trapezoid wave design, how often would the output wave change amplitude? 

    If possible, could you draw or plot the expected input and output response? If the amplitude changes slowly, this may be easier to realize. 

    Thanks,

    Jacob