EST Find Current IDs for NMOS-PMOS Circuit

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SUMMARY

The discussion focuses on calculating the drain current (Ids) for an NMOS-PMOS circuit using parameters from a simulation conducted in PSpice. The NMOS transistor has a transconductance parameter (Kp) of 500 µA/V² and a threshold voltage (Vto) of 1V, while the PMOS transistor shares the same Kp but has a Vto of -1V. The simulated values obtained were Ids = 2.75 mA and Vout = 4.32 V. The user struggled with applying the saturation formula and graphing the load line for the NMOS transistor, indicating a need for clarity on the equations governing MOSFET operation.

PREREQUISITES
  • Understanding of NMOS and PMOS transistor operation
  • Familiarity with PSpice simulation software
  • Knowledge of MOSFET saturation and linear region equations
  • Ability to graph load lines for transistor circuits
NEXT STEPS
  • Study the derivation of the MOSFET Ids equation: Ids = Kp * (Vgs - Vto)
  • Learn how to graph load lines for NMOS and PMOS transistors
  • Explore PSpice tutorials focused on MOSFET circuit simulations
  • Investigate the conditions for MOSFET operation in saturation and linear regions
USEFUL FOR

Electrical engineering students, circuit designers, and anyone involved in semiconductor device analysis will benefit from this discussion, particularly those working with NMOS and PMOS transistors in circuit simulations.

brad sue
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HI,
The teacher gave us an hint about a problem that might appear on an exam.
I was not able to solve it and I need some assistance pleas.
Find the current ids for the following circuit:
see attachment.

I have simulated the circuit with Pspice and I get the following values ids= 2.75[mA]
and Vout=4.32[V]

the paramter for the transistors were:
NMOS Kp=500 [uA/V^2]and Vto=1[V]

PMOS Kp=500 [uA/V^2] Vto=-1[V]

I tried the saturation formula but I did not find the values.

I also tried to use the load lines for the transistors but I had trouble graphing the load line for the NMOS (bottom transistor).
Please can someone help me please?
Thank you
B
 

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You have two unknown variables in this problem IDS and VO. You can also make two equations, one for each MOSFET. Like IDS = KP⋅(VGS - VTO). Find VGS in terms of the circuit voltages. Of course IDS will be the same for both transistors since there's no load.

You can start with the assumption that both devices are operating in their linear region, but then verify that is true after you get a solution.
 

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