IV characteristics for PMOS on cascade probe station

Hey guys,

I am trying to verify the IV characteristics of a PMOS on cascade's probe station along with Agilent's parameter analyzer.. I am using a CD4007UB chip for the same. The source of the PMOS is pin no 14 (VDD). The drain is a floating pin, and the gate is shorted with the gate of the NMOS. What values should I force through the gate, drain and source to receive the correct I-V characteristics?

Please let me know.

Thanks.

email id: nikhil.varghese31@gmail.com

Use it like an independent PMOS, i.e. ignore its gate connection to the NMOS gate. Sweep the (negative) drain voltage with Vgs as parameter, and measure the drain current.

erikl said:

Use it like an independent PMOS, i.e. ignore its gate connection to the NMOS gate. Sweep the (negative) drain voltage with Vgs as parameter, and measure the drain current.

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Thank you so much for replying Erik. I have to verify the NMOS and PMOS separately, therefore the NMOS is not connected at all. I tried sweeping Vgs from -5 to 0, drain voltage from -5 to 0 and gave 0V at the source. But I didn't get the desired results. Is it because the source of the PMOS is connected to VDD (pin 14)? Should I try any other values? The max voltage I can provide is + or - 5V. Please let me know.

Thanks again.

I think you need to supply the substrate: GND (pin 7)=0V , VDD (pin 14)=SRC=+5V , Vgs = +5..0V , Vds = +5..0V .

You could also try the same PMOS voltages as above, but GND (pin 7) = -5V .

erikl said:

I think you need to supply the substrate: GND (pin 7)=0V , VDD (pin 14)=SRC=+5V , Vgs = +5..0V , Vds = +5..0V .

You could also try the same PMOS voltages as above, but GND (pin 7) = -5V .

Click to expand...

Hey Eric,

Thanks.

For NMOS, I gave pin 7 (source) 0V, Vgs: 0 to 5V, Vd: 0 to 5V, and did not provide supply (Vdd) at all. I still managed to get the desired waveform.
For PMOS, is it necessary to ground pin 7?

Also, is there a way to determine whether the results that I received are correct? I tried looking at the datasheet for CD4007. But it doesn't show any data for MOSFETs. Is there anyway I can verify my results.

Please let me know.

Thanks so much for your help Eric. Really appreciate it.

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The thing is that, on Agilent's parameter analyzer, I can only put in values for the source, gate, drain and substrate. SMUs are connected to probes which are connected to the corresponding pins. For NMOS, where can i give the supply voltage? gate gets 0 to 5V (pin 6), source gets 0V (PIN 7), drain get 0 to 5 V (pin 8). Where can I connect VDD for the PMOS? The analyzer does not give me options to supply voltage anywhere else.

Nikhil678 said:

For PMOS, is it necessary to ground pin 7?

Click to expand...

Yes, I'd think so, because it's the chip's substrate.

Nikhil678 said:

Also, is there a way to determine whether the results that I received are correct? I tried looking at the datasheet for CD4007. But it doesn't show any data for MOSFETs. Is there anyway I can verify my results.

Click to expand...

The TI datasheet shows typ. and min. output characteristics on Fig. 5 & 8 resp. for the NMOS and on Fig. 9 & 10 for the PMOS.

Nikhil678 said:

For NMOS, where can i give the supply voltage? gate gets 0 to 5V (pin 6), source gets 0V (PIN 7), drain get 0 to 5 V (pin 8). Where can I connect VDD for the PMOS? The analyzer does not give me options to supply voltage anywhere else.

Click to expand...

You can put +5V at pin 14, but it's not really necessary in this case, I think.