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Lecture 2 NMOS Technology 240-451 VLSI, 2000
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Lecture 2 NMOS Technology VLSI, 2000
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Design Abstraction Levels
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Design Abstraction Levels VLSI, 2000
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Introduction to NMOS NMOS technology was divided into 3 layers :
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Introduction to NMOS NMOS technology was divided into 3 layers : - Diffusion Layer - Poly Silicon - Metal VLSI, 2000
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Introduction to NMOS 240-451 VLSI, 2000 D G G S D S
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Introduction to NMOS D S G G S D Poly cross with diffusion --> Field effect transistor (FET) VLSI, 2000
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The Basic Idea ... N-Channel - N-Switches are ON when the Gate is
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut The Basic Idea ... N-Channel - N-Switches are ON when the Gate is HIGH and OFF when the Gate is LOW P-Channel - P-Switches are OFF when the Gate is HIGH and ON when the Gate is LOW (ON == Circuit between Source and Drain) VLSI, 2000
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Transistors as switches
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Transistors as switches N Switch G S D 1 Passes “good zeros” P Switch G S D 1 Passes “good ones” VLSI, 2000
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โลหะไม่มีปฏิกริยากับเส้นอื่น Diffusion has C > Poly , Metal BUT!!
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut General Properties โลหะไม่มีปฏิกริยากับเส้นอื่น Diffusion has C > Poly , Metal BUT!! Poly and metal have R > Diffusion. VLSI, 2000
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Department of Computer Engineering, Prince of Songkla University
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut MOS Transistor VLSI, 2000
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Current and transistor structure
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Current and transistor structure G S D - + Vds Ids Vgd Vgs VLSI, 2000
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Current in transistor Ids = Q t S v E = Vds ; Vds low L t = L2 m Vds
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Current in transistor Ids = Q t S v L mE E = Vds ; Vds low L t = L2 m Vds VLSI, 2000
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I flow and transistor will be ON
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut t a L2 Ids a Vgs Vgs > Vthreshold ; I flow and transistor will be ON VLSI, 2000
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The relation between current and voltage
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut The relation between current and voltage VLSI, 2000
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Capacitance Q = - Cg (Vgs - Vth) * C = eA D Q = -eWL (Vgs - Vth) D
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Capacitance Q = Cg (Vgs - Vth) * C = eA D Q = -eWL (Vgs - Vth) D VLSI, 2000
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Current in Transistor (Ids)
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Current in Transistor (Ids) Ids = - meW (Vgs - Vth) Vds LD Vds = LD Ids meW (Vgs - Vth) R = L2 m Cg(Vgs - Vth) VLSI, 2000
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Current in Saturation Ids = meW (Vgs - Vth)2 2LD 240-451 VLSI, 2000 D
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Current in Saturation Ids = meW (Vgs - Vth)2 2LD G S D VLSI, 2000
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Current in Nonsaturated
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Current in Nonsaturated Ids = Cgm ((Vgs - Vth)Vds - Vds2 ) L VLSI, 2000
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N Channel: on=closed when gate is high
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Serial Parallel Structure (1) 1 G S D N Channel: on=closed when gate is high VLSI, 2000
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NMOS Transistors in serial/parallel connection
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut NMOS Transistors in serial/parallel connection Transistors can be thought as a switch controlled by its gate signal NMOS switch closes when switch control input is high VLSI, 2000
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P Channel: on=closed when gate is low
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Serial Parallel Structure (2) P Channel: on=closed when gate is low G S D VLSI, 2000
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PMOS transistors serial/parallel connection
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut PMOS transistors serial/parallel connection VLSI, 2000
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“Inverter in the next slide”
Department of Computer Engineering, Prince of Songkla University by Wannarat Suntiamorntut Questions & Summary “Inverter in the next slide” VLSI, 2000
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