how do i get the IV characteristic curve for a HEMT transistor using benchtop equipme

Discussion in 'General Electronics Chat' started by jacuna1012, Jun 16, 2012.

  1. jacuna1012

    Thread Starter New Member

    Jun 16, 2012
    I need to get the IV characteristic curve for a HEMT transistor using regular benchtop equipment like function generators, benchtop power supplies, multimeters, and oscilloscope. I have never done this physically. I had several attempts on doing this but I dont seem to know if I am doing this right. My transistor is a GaN HEMT number cgh40010 from CREE. The data sheet from CREE is confusing. I know that VGS controls the resistance of the transistor which influences the current IDS. My circuit consists of the transistor with a 2200 ohm resistor at the gate. This has a voltage from a power supply. The source terminal is grounded. There is a resistor on the drain terminal with a resistance of 75 ohms. After the resistor is a voltage source which provides VDD. I don't know if I need this resistor. I have taken measurements with VGS AT -3 v since the data sheet states that the minimum threshold voltage is -3 V. I not sure what that really means to my circuit. I have taken measurements with vgs fix at this voltage. I have measured the voltage vdd and vd(drain). To find the current I subtracted vdd and vd then took the result and divided it by the 75 ohm resistor. This current value seems realy small. When I plot IV using vd and id from calculation, my graph looks linear and does not curve. My power source indicates that as vdd increases, there is a high current being supplied to the circuit. This starts from 0A and reached about 160 mA. At this point the resistor and transistor starts to heat up. I dont go any further. I don't know why my iv plot does not look like other iv curves. It looks like I have not reached the saturation point. I would really appreciate any comments or advice.