Tài liệu Circuits & Electronics P25 pptx

6.002 Fall 2000 Lecture 1 25 6.002 CIRCUITS AND ELECTRONICS Violating the Abstraction Barrier 6.002 Fall 2000 Lecture 2 25 Case 1: The Double Take Problem R i V O V “0” Æ “1” t O V “0” “1” t O V “0” “1” observed expected in forbidden region! huh? 6.002 Fall 2000 Lecture 3 25 (a) DC case R i V O V 1 V very high impedance, like open circuit OK DCV5V i = DCV5V O = DCV5V 1 = 6.002 Fall 2000 Lecture 4 25 t V5.2= O V t i V (b) Step not ok! t 1 V looks ok! b.1 b.3 b.2 V0 V5 0= t 0=t 0=t T T2 V5 V5 R i V O V 1 V very high impedance, like open circuit O V 6.002 Fall 2000 Lecture 5 25 R i V instantaneous R divider finite propagation speed of signals characteristic impedance →R T2 T 5 2.5 0 V5 0 V5 0 V5 6.002 Fall 2000 Lecture 6 25 Question: So why did our circuits work? More in 6.014 t V5 V5.2 3. Termination P a r a l l e l t e r m i n a t i o n D E M O a d d R a t t h e e n d 0 V O 2. Keep wires short t V5 0 0 V O D E M O u s e s m a l l w i r e “ S o u r c e T e r m i n a t i o n ” 1. Look only at V 1 t 0 T V5 0 V 1 D E M O 6.002 Fall 2000 Lecture 7 25 Case 2: The Double Dip Problem Æ strange spikes on supply driving a 50 Ω resistor! V 0 1 0 1 OK Why? input driving a 50 Ω resistor! V 0 6.002 Fall 2000 Lecture 8 25 V dt Ldi Drop across inductor Inverter current v inductor solution 1. short wires 2. low inductance wires 3. avoid big current swings V S V S 6.002 Fall 2000 Lecture 9 25 Case 3: The Double Team, or, Slower may be faster! Problem a given chip worked, but was slow. Let’s try speeding it up by using stronger drivers actual ideal ideal C Disaster! L ω actual 6.002 Fall 2000 Lecture 10 25 Why? Consider crosstalk! 1 R 0 R DEMO 2 R C dt dV α DEMO ok dt dV C . 6.002 Fall 2000 Lecture 1 25 6.002 CIRCUITS AND ELECTRONICS Violating the Abstraction Barrier 6.002 Fall 2000 Lecture. 5 2.5 0 V5 0 V5 0 V5 6.002 Fall 2000 Lecture 6 25 Question: So why did our circuits work? More in 6.014 t V5 V5.2 3. Termination P a r a l l e l t e r