I'm trying to determine the minimum requirements for a MOSFET that will be used in a op-amp based current source. I've hit Google and this site and looked at multiple pages, but almost always, they are dealing with high voltage and/or current, so I'm not real sure they apply here.
This will be used in the output stage of an impedance analyzer. While I've got op-amps that will easily source the 30 mA(or less) that are required, I'm trying to in essence buffer the op-amp from any capacitance on its output.
The input to the MOSFET is a 3Vpp(or smaller), biased at 2.5V 100Khz(or less) sine wave. The application is a AFE for the AD5933 chip.
Please note, I'm not asking for a specific MOSFET, but for the things I should look for in choosing one. Yes, I do know about the so called linear MOSFETs, but I really think that they would be a massive overkill(and a budget buster, to say the least) in this application.
Just as an example, the SI2300(and I have 30 or 40 of them handy) has my requirements firmly within its SOA chart(which has a decent DC area). Is there anything else I should be looking at on the datasheet that would disqualify it for use here?
In any case, I'm planning on heat sinking the MOSFET however I can. In the above MOSFETs case, I was going to increase the area of the copper pads it is soldered to, and give it copper right below it. If it's a TO-220 or 253, it gets a real heat sink. Etc.
The power supply I'll be using has 5V(10A), 12V(3A) and -12V(800mA) available if that would make a difference.