Using an LT1357CN8 to amplify the signal of a 1.5 MHz frequency generator

Question

I am working on a frequency generator to control piezoelectric transducers. I use an Arduino Uno R4 Minima to send data to an AD9833 which creates my desired sine wave up to the required 1.5 MHz.

However, the output of the AD9833 is only 0.6 V, which is far below the sought after 30 V for the transducers. So I started researching signal amplification and found op-amps to be the solution to my problem.

I did the math (which you find below) to find one which should satisfy my needs, ordered them, however, now the signal is absolutely unusable. edit: thanks to user "Andy aka", I know I will not be able to go directly from 0.6V to 30V, I plan on using 2 consecutive OpAmps with a gain of 10: 0.6V -> 6V and the second with gain 5: 6V -> 30V this way I should be withing the bandwidth of the OpAmps

I ordered the LT1357CN8 and used it in a closed loop circuit to amplify the signal from the AD9833. The following three pictures showcase at (relatively) low frequencies of 1 kHz the sine wave is very nice, at 10 kHz you see the troughs starting to be dented and at high frequencies the bottom seems to be completely flattened.

How might I solve this problem? Is the op-amp limiting?

Calculation for an OPA828 which I found to be overkill for my case:

The schematic of my OpAmp circuit, Vsignal is the output of the AD9833, since this works fine I haven't added it in the schematic.

Answer 1

the output of the AD9833 is only 0.6 V, which is far below the sought after 30 V for the transducers.

That means you need a gain of 50.

However, the gain-bandwidth-product of the LT1357CN8 is only 25 MHz hence, if you want a gain of 50, the highest usable frequency will be 500 kHz but, you want 1.5 MHz: -

an AD9833 which creates my desired sine wave up to the required 1.5 MHz.

So, that's the problem.

How might I solve this problem? Is the op-amp limiting?

You need a much faster op-amp.

Answer 2

It finally worked, thanks to the tip of @qrk. Eventhough I used the + and - pole of the laboratory power supply, this didn't create a positive and negative voltage. So I used two batteries in series, set the middle as GND and had 2 voltage wires + and - 7.5V, the OpAmp finally amplifies the signal without distortion and the signal is a perfect sine wave.

The setup:

^{simulate this circuit – Schematic created using CircuitLab}