Download Assign. 2 for 2016/2017 File - e

FAKULTI KEJURUTERAAN ELEKTRIK
UNIVERSITI TEKNOLOGI MALAYSIA
SKEL 4283
Assignment 2
Oct. 2016
Use TSMC 0.25 µm process parameters in all your calculations. VDD is 2.5 V.
1.
Design a common-source amplifier with a current-source load with the following
design specifications: (you cannot design a circuit exactly the same with your
course mate)
VDD = 2.5 V
Vin
M2
Vout
VB





M1
both transistors are in saturation
L = 2 μm for both transistors
voltage gain ≥ 30
output resistance ≥ 100 kΩ
power consumption of the amplifier ≤ 0.1 mW
(a) Show all your calculations. Summarize your design in Table 1.
Table 1: CS design values
ID
Voltage gain
VIN
W1
W2
VB
(b) Simulate your circuit to obtain VTC (refer class note for SPICE code). Attach
VTC plot in your report.
(c) From your VTC plot, identify a value of VIN that ensures the circuit works as
an amplifier. Do not use your calculated VIN specified in Table 1. The circuit
is very sensitive to correct value of VIN. Modify the SPICE code to include the
correct value of VIN and then add the command to measure voltage gain and
output resistance (assuming output node is called out):
.tf v(out) vin
Simulate the circuit. Attach the transfer function pop-up window in your
report, and the SPICE code to obtain this result.
(d) Remeasure the gain using transient analysis. The SPICE code for transient
analysis is:
* assuming your VIN is 1.46 V
* define sine wave input: DC level of 1.46 V
* 0.5 mV peak (i.e. 1 mV p-p), 1 kHz frequency
vin
g1
0
sine(1.46 0.5m 1k)
* do transient analysis every 1 us, from 0 – 3 ms
.tran
1u
3m
Simulate the circuit. Show both plots of input and output signals on two
separate plot panes and calculate the gain by measuring the peak-to-peak
output signal amplitude. Attach both plots in your report.
Marking scheme:
2.
Q1
40 marks
Saturation not proven
Table 1 not included
VTC simulation output not included
Transfer function simulation output not included
SPICE code to obtain transfer function not included
Plots from transient simulation not included
Specifications not met
Similar design to another course mate
-5 mark
-10 marks
-5 marks
-3 marks
-2 marks
-5 marks
-10 marks
-30 marks
Final exam 2013/2014 II
A new version of CS amplifier with push-pull load is shown below.
VDD = 2.5 V
M3
vOUT
vIN
M2
M1
(a) Draw a small signal equivalent circuit for the amplifier. Do not neglect the
body effect. Simplify your circuit.
(b) Based on your small signal equivalent circuit that you have drawn, write
circuit equations in order to find the DC voltage gain AV = vout/vin. Do not
solve your equations.
Marking scheme:
(a)
(b)
5 marks
5 marks
3.
Consider the source follower circuit below. We want to set the DC voltage at the
output VOUT = 1 V. In all your calculations, you can ignore  but do not ignore
body effect.
VDD = 2.5 V
Vin
M1
W 1 8m

L1 1m
Vout
RS
10 kΩ
(a) Determine the DC voltage at the input, VIN.
(b) Calculate gm.
(c) Calculate gmbs.
(d) Calculate voltage gain AV = vout/vin.
(e) Calculate output resistance Rout.
(f) Simulate the circuit to measure voltage gain and output resistance (use .tf
SPICE command). Attach the transfer function pop-up window in your
report, and the SPICE code to obtain this result.
Marking scheme:
Q3
20 marks
Saturation not proven
gm not calculated
gmbs not calculated
AV not calculated
Rout not calculated
Transfer function simulation output not included
SPICE code to obtain transfer function not included
-5 mark
-3 marks
-3 marks
-3 marks
-3 marks
-3 marks
-2 marks
4.
Problem 3.21 from Razavi textbook (1st ed).
Assuming all MOSFETS are in saturation, calculate the small-signal voltage gain
of the circuit in Fig. 3.73(f). Assume γ = 0. You can also assume gm >> gds, so for
example gm2 + gds1 ≈ gm2.
Marking scheme:
15 marks