Exam text content

 

Exam-1 on Micro-Electronics-1, EE.ELE.270, Period-3, Spring-2024

TITLE: Design a NMOS Common Source Amplifier with PMOS Current-Source Load
TASKS:

NOTE: The answers/solutions should include Explanations, Schematic pictures and the relevant Simulation Results.
Add also the Operating Point Voltages and Currents on the schematic by using Data Labels.

1) In the table of choices you have receved an exact NMOS transistor sizes (L and W) and specified Bias Point: Drain-Current and Drain-Source
Voltage of operation. Plot the NMOS transistor Output V/A Characteristics (Id as function of Vds and parameter Vgs) and also its Transfer V/A
Characteristics (ld as function of Vgs and parameter Vds). What is the Threshold Voltage of the NMOS transistor ? Find and write down the needed
Gate-Source Voltage (within 10mV accuracy) which you should apply to the NMOS to operate at the requested Bias Point.

2) Please design the W and the L of a PMOS transistor, which matches (in a manner explained in Exercise # 3 and 4) the given NMOS in the way that the
PMOS would operate at the same absolute values (but in reversed polarity) of Drain-Current, Drain-Source Voltage and Gate-Source Voltage, as the
given the NMOS. Keep in mind that both transistors should have similar ro (as represented by the slope of their output characteristics, Id (Vds, Vgs) ).
Plot the Output V/A Characteristics of the PMOS (Id as function of Vds and parameter Vgs), and also its Transfer V/A Characteristics (Id as function of
Vgs and parameter Vds ). What is the Threshold Voltage of the PMOS transistor ? How large (in kOhms) is the achived value of the ro of the PMOS at
the bias point as seen in LT-Spice ?

3) Use the transistors from task '1)' and taks '2)' to design a common source amplifier with NMOS as input and PMOS as current source load (as
explained in Exercise #4). Use ideal! voltage sources for biasing of NMOS and for PMOS. Use supply voltage Vdd = 2*Vds (twice the value of Vds). Plot
the Amplifier Voltage-Gain versus Frequency (AC simulation ) and find out the achieved -3dB corner frequency.

4) Add a source resistance RS = 5000 and load resistance RL = 180k to the amplifier. Plot the Voltage-Gain versus Frequency (AC simulation ) and
find out the achieved -3dB corner frequency. Run also transient simulation with input signal amplitude of 1OmV and frequency 1MHz.

5) In the Circuit of point '4)' add capacitor in parallel with the load resistor and perform Parametric Simulation to evaluate the gain with
capacitances of 100fF, 200fF, SOOfF, IpF and 2pF.

6) Design the Bias Circuitry of the entire amplifier using Current Mirrors for the amplifier in task '3)', using some of the circuit configuration examples
discussed during the Exercises (e.g. Execise #5).