Copyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Lecture 15: October 22, 2001Logic with a State Dependent DeviceA)State Dependent Device IOUTvs. VOUTB) Load Line Analysis for Logic LevelsC)Voltage Transfer CharacteristicsVTC = plot of VOUTvs. VIND) 42 Pull Down (42PD) Device and LogicReading: Schwarz and Oldham pp. 593-595, 604-606 (read for graphs and not physics)Reminder:20 Minute Quiz Wed. Oct. 31 in class2ndMidterm Wed. Nov. 7 in classCopyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Logic Gates – How are they built in practice?What goes in this box?How does it affect digital performance?Pull up NetworkVSUPPLYGroundArray of ValvesVINSignalsA,B,CVOUTA Valve is a TransistorValves in Parallel => NORValves in Series => NANDABCurrent flows when VINis highCan be modeled by a 10kΩ resistorVINABCIN= 100 fFFan OutCopyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Digital Logic from State-Dependent Three-Terminal DevicesThree-terminal devices such as MOS transistors have characteristics (such as IOUTvs. VOUTcurves) on the output side that can be programmed by changing signals on the input side (such as the input voltage).The input can thus be viewed as changing or programming the ‘State’ of the output of the device.Three-terminal devices whose ‘State’ can be programmed can be used to make digital logic devices for computers that respond to input signals.Copyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01State-Dependent Three-Terminal Device ElementVOUTInput for ControlSignal to set the StateIOUTOutputVINCopyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01State-Dependent Device IOUTvs. VOUTVOUT(V)035State 1IOUT(µA)2060100State 3State 5Depending on the state IOUTvs. VOUTis constrained to be on one of these curves by the three-terminal device.Only three states are shown but typically there is a continuum of states.Copyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Three-Terminal Device Logic CircuitVDDVOUTInput for State ControlSignalIOUTOutputVINRPULL UPCopyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Thevenin Model For Pull-Up DeviceVTHEVENIN= VDDIOUT SHORT CIRCUIT= (VDD/RPULL UP)VOUTIOUTOutputVDDRPULL UPExample:VDD= 5V and RPULL UP= 100kΩVTHEVENIN= 5VIOUT SHORT CIRCUIT= 50 µAThevenin looking this wayCopyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Thevenin Model For Pull-Up DeviceIOUT(µA)2060100VTHEVENININORTONIOUTvs. VOUTFor the Pull-Up Resistor and VDDVOUT(V)035IOUTvs. VOUTis constrained to be on this line by the circuit external to the three-terminal deviceCopyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Composite Current Plot for the Logic CircuitThree-Terminal Device Plus Load Line for the Pull-Up DeviceVOUT(V)035State 1IOUT(µA)2060100State 3State 5INORTONVTHEVENINIOUTvs. VOUTFor a given state only one point satisfies both the external circuit and the three-terminal deviceNote that when VOUTis low current flows and power is consummedCopyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Voltage Transfer Function: VOUTvs. VINVOUT(V)VIN(V)035350State 1State 3State 5Inverting typeVOUT(V)VIN(V)035350State 1State 3State 5Noninverting typeThe VOUTvs. VINcharacteristic is another view of the logic gate that is used to determine the inverting and noninverting nature of a gate.Copyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Voltage Transfer Function for the Logic CircuitVOUT(V)VIN(V)035350State 1State 3State 5VOUTIOUTOutputVINVDDRPULL UPCopyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/0142Pull-Down Device Model IOUTvs. VOUTVOUT(V)035State 1IOUT(µA)2060100State 3State 5Cut-offLinear (with VOUT)Saturation (with VOUT)Copyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/0142Pull-Down Device Equations Describe IOUTas function of VINand VOUT0=OUTI() ()OUTINOUTTINOUTVVVAVVVkI 1252−=−=µ() ()TINTTINOUTVVVAVVVkI 125 −=−=µCut-offVVVTIN1=≤Linear (with VOUT)VVVTIN1=≤VVVTOUT1=≤Saturation (with VOUT)VVVTIN1=≤VVVTOUT1=≥Values shown for VT= 1V and k = 25 µA/V2Copyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Composite Current Plot for the 42PD CircuitVOUT(V)035State 1IOUT(µA)2060100State 3State 5VTHEVENIN (Open Load)INORTON (Open Load)VOUTIOUTOutputVINVDDRPULL UPCopyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Composite Current Plot for the 42PDCircuit with 200kΩ Load to GroundState 1VOUT(V)035IOUT(µA)2060100State 3State 5VTHEVENIN (Open Load)INORTON (Open Load)VTHEVENIN (200KΩ Load) = 3. 3 VINORTON (200KΩ Load)VOUTIOUTOutputVINVDDRPULL UPRLOAD(200KΩ)Copyright 2001, Regents of University of CaliforniaEECS 42 Intro. electronics for CS Fall 2001 Lecture 15: 10/22/01 A.R. NeureutherVersion Date 10/22/01Voltage Transfer Function for the 42PD Logic Circuit w/wo LoadVOUT(V)VIN(V)035350State 1State 3State 5Open Load200 KΩ LoadComplete this VTC for the 42PD device in the
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