VLSI EXAM 1 LATEST UPDATED
What happens when the Vdd of a CMOS inverter is reduced? - ANSWER 1.
Noise margin reduces
2. Drain current reduced which will drop propagation delay
3. Rise and fall time of output increases
What are the attributes of the subthreshold current in MOSFET? - ANSWER
1. Subthreshold current increases with an increase in temp
2. DIBL reduces the barrier thus subthreshold current increases with increased
DIBL
3. Subthreshold current increases with the width of MOSFET
What are the attributes for DC Gain of a CMOS inverter? - ANSWER 1. The
gain will always be negative!
2. The magnitude of gain must be > 1 in the transition region
3. Magnitude of |g| < 1 away from transition region
What is a T-1 network? - ANSWER rL/2 CL rL/2 T
What will a +Vbs do to a PMOS - ANSWER Vth will decrease, PMOS
becomes stronger
What will a -Vbs do to a PMOS - ANSWER Vth will increase, PMOS
becomes weaker, less current flow
What happens when the Vdd of a CMOS inverter is reduced? - ANSWER 1.
Noise margin reduces
2. Drain current reduced which will drop propagation delay
3. Rise and fall time of output increases
What are the attributes of the subthreshold current in MOSFET? - ANSWER
1. Subthreshold current increases with an increase in temp
2. DIBL reduces the barrier thus subthreshold current increases with increased
DIBL
3. Subthreshold current increases with the width of MOSFET
What are the attributes for DC Gain of a CMOS inverter? - ANSWER 1. The
gain will always be negative!
2. The magnitude of gain must be > 1 in the transition region
3. Magnitude of |g| < 1 away from transition region
What is a T-1 network? - ANSWER rL/2 CL rL/2 T
What will a +Vbs do to a PMOS - ANSWER Vth will decrease, PMOS
becomes stronger
What will a -Vbs do to a PMOS - ANSWER Vth will increase, PMOS
becomes weaker, less current flow
