Question

Assume the following unless stated otherwise for a 0.25 μm CMOS process:

VDD=5V, Lₘᵢₙ=0.25 μm
Vₜₙ=0.5 V or -1V (choose accordingly), Vₜₚ=-0.5 V
μnCₒₓ=265 μA/V², μpCₒₓ=90 μA/V²
Consider a depletion-mode NMOS loaded inverter.
a) Design the inverter so that VOL=0.015 V.

Answer 1

To design an inverter with a VOL of 0.015 V in a 0.25 μm CMOS process, one must select the appropriate NMOS transistor size, taking into account the given threshold voltage and transconductance parameters.

Step-by-step explanation:

The question pertains to the design of a depletion-mode NMOS loaded inverter in a 0.25 μm CMOS process. To design an inverter that achieves a VOL of 0.015 V, one must consider the threshold voltage (Vt) of the NMOS, which, based on the information provided, can be assumed to be 0.5 V. The design process involves selecting a suitable size (width to length ratio) for the NMOS transistor to ensure that in the on-state, it can pull the output down to 0.015 V. The transconductance parameters (μnCox for NMOS and μpCox for PMOS) are also taken into account, which can influence the sizing of the transistors for desired current-driving capabilities.