EE477-hw3-solutions-nazarian-spring2009

EE477-hw3-solutions-nazarian-spring2009 - EE 477L Homework...

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1 EE 477L Homework 3 Solutions Spring ’09 Nazarian Lecture 9:30 Assigned: Tuesday Feb. 24, 2009 Due: March 6, 2009 EEB340 at 11am Show and explain your work clearly and in detail . Write the parameter units right beside their numerical values in your equations to show that the final result has the right unit (e.g., for N A =10 17 1/cm 3 write N A /q as 10 17 [cm -3 ] / 1.6×10 -19 [C] = 10 17 /(1.6×10 -19 ) [ 1/(cm 3 C) ] .) 1. Figure 1 shows an enhanced-load NMOS inverter. Assume γ =0.4, 2| φ f|=0.6V, V T0 =0.43V k n ’=115μA/V 2 and λ =0, (Note: all the following questions are adopting this information unless otherwise stated), calculate V OH , V OL , V M for the inverter and also the noise margin. Figure 1 Solution V OL : To calculate V OL , we set V IN = V DD = 2.5V. We expect V OUT to be low, so we can make the assumption that M2 will be saturated and M1 will be in the linear region.
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2 For M2: ' 2 2 22 2 2 .. ( ) . ( 1 ) 2 n DG S T D S k W IV V V L λ =− + , whereby 2 T V can be approximated as 2 T V derived in above process, which is equal to 2.5-1.765=0.735(V). For M1: ' 2 1 11 1 1 1 1 [ 2 ( ) ] 2 n D GS T DS DS k W V V V L Set 2 D I = 1 D I , we get OUT V =0.285V. (Hint, more accurately, we can still consider the body effect of M2, and form 2 equations to solve both OUT V and 2 T V , which is also considered to be correct) V M : To calculate V M we set V M = V IN = V OUT ; therefore both M1 and M2 are in saturation region since their V G = V D , and we have following equations: ' 2 2 2 2 ( ) . ( 1 ) 2 n S T D S k W V V L + = ' 2 2 2 ( 0 . 7 3 5 ) 2 n DD M k W VV L −− ' 2 1 1 1 ( ) . ( 1 ) 2 n S T D S k W V V L + = ' 2 1 0 1 ( ) 2 n MT k W L Set 1 D I = 2 D I , we get M V = 0.984V. 2. Consider a standard CMOS inverter with V OH =2V, V OL =0.1V, while its V IH and V IL values are the same as those for the inverter in question 1. Comment on and compare the robustness of the two inverters.
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This note was uploaded on 07/21/2010 for the course EE- 477 taught by Professor Shahinnazarian during the Spring '09 term at USC.

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EE477-hw3-solutions-nazarian-spring2009 - EE 477L Homework...

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