Hi everyone,

I am looking to design an analogue modulator with a bandwidth of over 10MHz for OFDM signal transmitted by LED. I try to transmit sinusoidal signal which is generated by function generator to prove my design. Based on experiment, by using common emitter we get square output from sinusoidal input signal.

Then, I am not so sure wether a Push pull configuration or current sink is the best option.
Can anyone help with the correct design? also suitable components (such as OP-AMP, BJT, MOSFET) please.
I attached the figure of my electronic circuit below

Thank you.

 

You need to limit the current going into the LEDs. Neither of the circuits you posted do that.

You said that you need to drive the LED with a 10 MHz sine wave. Driving with pulses should be a lot easier, especially at 10 MHz.

Are you sure you need linearity, or can you drive the LED with pulses?

If you can drive with pulses there are many examples available
https://www.google.co.th/search?q=f...grIV7uIGImo0gST64eICg#q=fast+led+pulse+driver