lec15DSM - Introduction to CMOS VLSI Design MOS Behavior in...

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Introduction to CMOS VLSI Design MOS Behavior in DSM
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MOS Behavior in DSM Slide 2 CMOS VLSI Design Outline Transistor I-V Review Nonideal Transistor Behavior Velocity Saturation Channel Length Modulation Body Effect Leakage Temperature Sensitivity Process and Environmental Variations Process Corners
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MOS Behavior in DSM Slide 3 CMOS VLSI Design Ideal Transistor I-V Shockley 1 st order transistor models ( 29 2 cutoff linear saturatio 0 2 2 n gs t ds ds gs t ds ds dsat gs t ds dsat V V V I V V V V V V V V V β < = - - < -
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MOS Behavior in DSM Slide 4 CMOS VLSI Design Ideal nMOS I-V Plot 180 nm TSMC process Ideal Models β = 155(W/L) μ A/V 2 – V t = 0.4 V – V DD = 1.8 V I ds ( μ A) V ds 0 0.3 0.6 0.9 1.2 1.5 1.8 100 200 300 400 V gs = 0.6 V gs = 0.9 V gs = 1.2 V gs = 1.5 V gs = 1.8 0
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MOS Behavior in DSM Slide 5 CMOS VLSI Design Simulated nMOS I-V Plot 180 nm TSMC process BSIM 3v3 SPICE models What differs? V ds 0 0.3 0.6 0.9 1.2 1.5 V gs = 1.8 I ds ( μ A) 0 50 100 150 200 250 V gs = 1.5 V gs = 1.2 V gs = 0.9 V gs = 0.6
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MOS Behavior in DSM Slide 6 CMOS VLSI Design Simulated nMOS I-V Plot 180 nm TSMC process BSIM 3v3 SPICE models What differs? Less ON current No square law Current increases in saturation V ds 0 0.3 0.6 0.9 1.2 1.5 V gs = 1.8 I ds ( μ A) 0 50 100 150 200 250 V gs = 1.5 V gs = 1.2 V gs = 0.9 V gs = 0.6
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MOS Behavior in DSM Slide 7 CMOS VLSI Design Velocity Saturation We assumed carrier velocity is proportional to E-field v = μ E lat = μ V ds /L At high fields, this ceases to be true Carriers scatter off atoms – Velocity reaches v sat Electrons: 6-10 x 10 6 cm/s Holes: 4-8 x 10 6 cm/s Better model E sat 0 0 slope = μ E lat ν 2E sat 3E sat ν sat ν sat / 2 lat sat sat lat sat μ μ 1 E v v E E E = = +
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MOS Behavior in DSM Slide 8 CMOS VLSI Design Vel Sat I-V Effects Ideal transistor ON current increases with V DD 2 Velocity-saturated ON current increases with V
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This note was uploaded on 10/13/2009 for the course ECE 482 taught by Professor Adnanaziz during the Spring '07 term at University of Texas at Austin.

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lec15DSM - Introduction to CMOS VLSI Design MOS Behavior in...

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