6 002 CIRCUITS AND ELECTRONICS State and Memory Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 Review Recall vI v I VI for R C vC vC 0 t 0 t vC VI vC 0 VI e RC 1 Reading Sections 10 3 10 5 and 10 7 Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 This lecture will dwell on the memory property of capacitors For the RC circuit in the previous slide vI vI VI t 0 t 0 vC VI t vC VI vC 0 VI e RC vC 0 0 t Notice that the capacitor voltage for t 0 is independent of the form of the input voltage before t 0 Instead it depends only on the capacitor voltage at t 0 and the input voltage for t 0 Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 State State summary of past inputs relevant to predicting the future q CV for linear capacitors capacitor voltage V is also state variable state variable actually Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 State Back to our simple RC circuit 1 vC f vC 0 vI t vC VI vC 0 VI e t RC Summarizes the past input relevant to predicting future behavior Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 State We are often interested in circuit response for zero state vC 0 0 zero input vI t 0 Correspondingly zero state response or ZSR vC VI VI e t RC 2 zero input response or ZIR vC vC 0 e t RC 3 Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 One application of STATE DIGITAL MEMORY Why memory Or why is combinational logic insufficient Examples Consider adding 6 numbers on your calculator 2 9 6 5 3 8 M Remembering transient inputs Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 Memory Abstraction A 1 bit memory element d IN store M d OUT The 6 004 view The NEC View Remembers input when store goes high Like a camera that records input dIN when the user presses the shutter release button The recorded value is visible at dOUT d IN store remembers the 1 d OUT Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 Building a memory element A First attempt dIN dOUT C storage node store Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 Building a memory element A vC d OUT dIN store 1 C vC d OUT dIN store 0 C vC Stored value leaks away vC 5 e 5V VOH t t RL C T RL C ln RL VOH 5 from 2 T store pulse width RON C Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 Building a memory element B Second attempt dIN buffer dOUT C RIN buffer store Input resistance RIN VOH T RIN C ln 5 RIN RL Better but still not perfect Demo Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 Building a memory element C Third attempt buffer refresh store dIN dOUT store C Does this work No External value can influence storage node Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 Building a memory element D Fourth attempt buffer decoupled refresh store dIN dOUT C store Works Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 A Memory Array 4 bit memory IN store Address OUT Decoder 00 01 A d IN S M d OUT B d IN S M d OUT A C d IN S M d OUT B D d IN S M d OUT C a0 a1 2 Address 10 11 IN store D OUT Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 Truth table for decoder a0 0 0 1 1 a1 0 1 0 1 A 1 0 0 0 B 0 1 0 0 C 0 0 1 0 D 0 0 0 1 Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14 Agarwal s top 10 list on memory 10 9 8 7 6 5 I have no recollection Senator I forgot the homework was due today Adlibbing ZSR I think therefore I am I think that was right I forgot the rest Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY 6 002 Fall 2000 Lecture 14
View Full Document
Unlocking...