DC Transfer Curve
And its applica4ons
Basic Transistor Equa4ons
DC Transfer curve
Rela4on between Vout and Vin under DC condi4ons
Graphical Approach
The transfer curve
Transistor’s regimes of opera4on
Current drawn from supply
Vinv: Inverter Trip Point
Vinv
Skewed Inverters
Vinv
Lo-‐Skew
Hi-‐Skew
Process Varia4ons
• Threshold voltages are random variables – Gaussian pdf is a good approxima4on
• Consequantly, inverter trip point (Vinv) – Is also a random variable – As are other characteris4cs which depend on threshold
Voltage to logic levels
Noise Margin Defini4ons
Indicates tolerance to noise
Why is there noise?
• DC Noise due to sta4c voltage drops in the power grid
• AC noise: – due to coupling of switching signals – Transients in power grid
Importance of gain
• Larger gain beUer noise margin • Restoring effect of logic levels in a long chain • Large Vt – beUer gain
Sta4c Noise Margin for Memory Cell
BuUerfly Diagram