1. Applications of MOS Transistors in Digital Integrated Circuits (1)
Section 15.1

2. ADD an Instance of NMOS
NMOS transistor

3. A Simple Switching Circuit
variable DC voltage

4. Threhold Voltage
Threshold voltage of T0

5. Design variable
Library Setup

6. A Primitive Inverter Circuit
Large VDS
SATURATION
Small VDS :Triode

7. Determine Region of Operation
OFF
SATURATION
TRIODE

8. Determine Kn and Vth
Need to select drain terminal in order to get current

9. Derivation ID=0.5 unCox(W/L)(VGS-VTH)2 Find VTH
SQRT(2ID/(unCoxW/L))=VGS-VTH
The VGS that yields 0 LHS is the threshold voltage
SQRT(ID)=SLOPE(VGS-VTH)
SLOPE=SQRT(0.5 unCox(W/L))
This example: W/L=2um/1um=2
SLOPE=SQRT(unCox)

10. To Calculate Kn,find SQRT(ID)
The x interscept gives Vth
Vth (this method)=150 mV
Vth(Cadence)=164 mV

11. Find Kn=W/LunCox SQRT(ID) dSQRT(ID)/dVGS
This curve implies that unCox depends on VGS!

12. Noise Margin
Noise Margin: the maximum amount of noise at the input that can be tolerated before the output is affected significantly.
attenuating
attenuating
amplifying
dVout/dVGS
NML
NMH
dVout/dVGS=small signal gain

13. Generate Random Noise in Matlab

14. Inverter In the Presence of Noise
Relatively clean output
400 mV peak to peak noise
Time Scaling Factor

15. Inverter In the Presence of More Noise
1 V peak to peak of noise

16. Noisy Input
Relatively Clean Output

17. Adding a Capacitor to the Output
RC time constant

18. Ring Oscillator
1nF
oscillation

19. Ring Oscillator with Output Capacitor Load of 10 nF