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5.2a Poly Resistor • Value of resistor is from Problem 5.1=1KΩ • Sheet resistance of poly=25Ω/ • Thus number of squares in poly resistor=1KΩ/25Ω/ =40 • Therefore L/W=40. • Minimum feature size (2l)=2mm • Thus if we assume width of poly resistor to be 2mm then length of the resistor is 80mm. 1 Steps in Layout of Resistor • Since the minimum dimension in question 5.2 is 2mm. Therefore we should use the technology file corresponding to l=1mm 2 Resistor Layout There are 5 long sections of length 17l and width 2l Thus the number of squares is (5x17)/2~42 Also the edges contribute another 4 squares There is additional resistance due to current crowding at the corners and also the poly contact regions add additional resistance. 3 • W/L of nfet was 90 • Since L is 2l=2mm, W=180mm (90x2l) • Remember to account for Ld (lateral diffusion) in L of NMOS 4 Extraction • Once layout is drawn, DRC cleared and saved, it is ready to be extracted • Go to tools and click on extract • The window shown will appear. In the definition file tab, choose the appropriate technology file from the folder it is present by browsing. • Then hit run, the extracted output file can be opened with notepad. 5 Extracted file The extracted file will look as such This is the information required from extracted file to be used in spice Note: L=2.5mm to account for lateral diffusion mentioned in q.5.2 6 Pspice • First draw the circuit. Choose MbreakN part and place it. – Goto edit and click on model – Choose the Edit instance model (text) – Add the model parameters as below and click ok .model NMOD NMOS ( LEVEL=1, VTO=1 GAMMA=0.2 KP=20U) *$ – Also double click on part and change the attributes according to extracted Ledit file – Other parameters and other level models can also be added for more complex simulations • Finish the circuit by adding the dc source 7 Analysis • Choose dc sweep analysis • Click on the this tab and choose the voltage source to be swept and its range • Here the input voltage name is V3 and it was initialized to 0V 8 DC Sweep response 9 VIL,VIH determination The blue curve represents dVout/dVin, the markers point to where the slope is -1 VIL=1.5V, VIH=3.09V 10