tesseract
Newbie level 3
1 mhz power amplifier
Hey all. A physics professor friend of mine asked me to build an amplifier that could deliver 300Vpp across a purely capacitive load (literally, alternately polarized plates in a vacuum) with a 100kHz to 1MHz sine wave. This didn't seem like a very challenging problem to solve at first but now I think I may have dismissed it a bit too readily!!!
I realize that I could resonate out the load capacitance with a series inductance (detuned to a moderate Q with a series resistance) and greatly relax the amplifier requirements, but the people that will be operating it are a bunch of physics grad students who, you might guess, can't be counted on to properly tune the inductance each time they change frequency, so I'm trying to avoid this as much as is possible or practical. That said, I'm thinking I'll either have to go with a single ended Class A design, or else a high speed (i.e. - current feedback) op-amp driving a voltage gain then a current gain stage (probably with switching MOSFETs for the power devices in each), because these designs don't care what the VSWR of the load is. Am I on the right track here, or is there a practical way to employ a much simpler push-pull amplifier style that is frequently used in RF???
Thanks for any comments!
Hey all. A physics professor friend of mine asked me to build an amplifier that could deliver 300Vpp across a purely capacitive load (literally, alternately polarized plates in a vacuum) with a 100kHz to 1MHz sine wave. This didn't seem like a very challenging problem to solve at first but now I think I may have dismissed it a bit too readily!!!
I realize that I could resonate out the load capacitance with a series inductance (detuned to a moderate Q with a series resistance) and greatly relax the amplifier requirements, but the people that will be operating it are a bunch of physics grad students who, you might guess, can't be counted on to properly tune the inductance each time they change frequency, so I'm trying to avoid this as much as is possible or practical. That said, I'm thinking I'll either have to go with a single ended Class A design, or else a high speed (i.e. - current feedback) op-amp driving a voltage gain then a current gain stage (probably with switching MOSFETs for the power devices in each), because these designs don't care what the VSWR of the load is. Am I on the right track here, or is there a practical way to employ a much simpler push-pull amplifier style that is frequently used in RF???
Thanks for any comments!