[SOLVED] PWM Voltage Amplifier

[turtlepokerman]

Good Day Everyone,

I am currently looking for a way to amplify a 5Vpeak, 300 kHz PWM signal that will draw approximately 100nA to have a Von of 60V and a Voff of 0V. I have looked at operational amplifiers but have not had any success finding such a device. If anyone knows of a device or another method to amplify this signal please let me know. I need it to amplify the gate voltage on a NMOS device that drives a buck converter.

Thanks

 

[crutschow]

Operational amplifiers are generally for low level, low frequency analog signals and are not appropriate for amplifying high-frequency, high-voltage switching signals.

Is this for a high-side driver for the series switch in a positive output buck regulator? For that you can use a bootstrap, high-side mosfet driver such as the IR2117.

 

[turtlepokerman]

This is what I am constructing with the appropriate values and requirements:


From a analog design class I know that I have to meet certain criteria to have the MOSFET operate between Saturation and Cutoff Mode. I also know that enhancement MOSFET are in cutoff when zero volts are applied to the gate. To represent this I created a MATLAB file that represents the different gate voltages with Vd=108V and Vs = 36V. This shows me what voltages I need to operate between saturation and cutoff. In order to represent cutoff from 0V to gate I also made it so that every odd number voltage turns to 0V. Although not well represented on the plot. See below.


My question is how do I achieve a gate voltage that is high enough to chop the signal and operate at 300kHz. I have never heard of bootstrapping, but if that will for sure work for my scenario please let me know.

Thanks for everyones help,

 

[mtwieg]

As crutschow mentioned, there are specific ICs designed for this purpose, called bootstrapping high side gate drivers. They are not amplifiers per se, but rather high current digital drivers with an output designed specifically for driving circuits like yours.

 

[turtlepokerman]

I never knew these things existed. They sound awesome.

Thanks