hello everyone,
thanks in advance for taking the trouble to read and reply
i am struck with a circuit here . i am aiming to produce a triangular current waveform which has to be used in a different circuit . i've given the simplified version of the circuit
i am currently using MOSFET IRFP 250N. my gate drive voltage is a 5 V variable supply given from my computer(Vgs)
i am getting a linear current (Id) output when gate supply in the range of 3.5 to 3.9 and then it is suddenly shooting up and after that i am again getting a linear variation . This results in the distortion of my current waveform and so i am not able to implement it in my other circuitry
could you please help me with this problem or is there any other way to produce such a pulse like using IGBT or any other power device . please help
The amount of current out of a Mosfet is not linearily controlled by its gate voltage. An opamp could be used to provide plenty of gain so that negative feedback will make its response very linear.
are you suggesting a transconductance amplifier ? if so would it be stable for the current ratings that i specified (0-10A) and would it respond to a fast changing pulse of frequency 10 KHz .
and is it possible to obtain a gain of nearly 2A/V
i would be very glad if you can point out a suitable op-amp or atleast specify a link where i would get some info
Here is a linear amp with your Mosfet providing up to 30A to a load. Its voltage gain is 2 but is easily changed by changing one of the feedback resistors. It will faithfully reproduce a triangle wave or any other shape of wave up to about 15kHz.
EDIT: Voltage gain is 2, not 1.