V1
Schematic of the circuit
Case 1
Case 1:
ID vs Vds for M2 transistor (the lower transistor) for 9 different widths (0.18um to 100um)
while M1 width ( the top transistor) is fixed at 0.24um
Justification for case 1 graphs
•
Impact of Transistor Width (W):
•
Increasing Width: As the width (W) of the lower transistor (M2) increases in your simulations, the drain current (ID) is expected to increase
proportionally in each curve.
•
Wider Channel: Wider transistors provide a larger cross-sectional area for the conducting channel, allowing more current carriers (electrons) to flow
when biased in saturation. This results in a higher drain current for wider transistors compared to narrower ones at the same gate-source voltage
(VGS).
•
Observations on the Graphs:
•
The nine curves in the plot should visually confirm this trend. Wider transistors (larger W values) should correspond to higher ID values across the VDS
range (assuming they are all biased in saturation).
•
The curves might start diverging from each other at lower VDS values (linear region) and become more pronounced as VDS increases (saturation
region).
•
Additional Factors:
•
Aspect Ratio (W/L): While the width is varied, keep in mind that the length (L) of the transistor might also play a role. The aspect ratio (W/L) can
influence the transistor's characteristics.
•
Model Parameters: The specific model parameters used for the NMOS transistor in your simulation can also affect the exact shapes and slopes of the
curves.
•
Overall Justification:
•
The expected behavior is that the drain current (ID) will increase with increasing width (W) of the transistor for a given gate-source voltage (VGS) in
saturation just as shown in the graph.
Case 2
Case 2:
Id vs Vds for M1 transistor (the top transistor) for 9 different widths (0.18um to 100um)
while the lower transistor m2 is fixed at width 0.24um.
Justification for case 2 graphs
• Impact of Top Transistor Width (W):
• Unlike the case with the lower transistor (M2), the impact of varying the top transistor's width
(W) on the drain current (ID) of the lower transistor (M2) is less direct. Here's why:
• In this configuration, the top transistor (M1) primarily acts as a current source for the lower
transistor (M2). It sets the current that can flow through M2, assuming both transistors are biased
in saturation.
• If the gate-source voltage (VGS) of M1 remains constant across different width variations, the
current it allows to flow will also remain relatively constant (assuming the model operates in
saturation).
• Observations on the Graphs:
• The nine curves representing different widths of M1 should ideally overlap or show minimal
variations in the drain current (ID) of M2 across the VDS range.
• There might be slight variations due to model complexities or non-idealities, but the overall trend
is a relatively constant ID for all width values of M1.