EEC 116 - Homework 5

Do your work individually. For this assignment, use standard magic design rules plus the EEC 116 Nanometer-scale rules.

240 pts total.

  1. [15+15 pts] A certain material has R_square = 0.12 Ω when it is 1.00 μm thick. The material is patterned into the shape shown below and is 0.025 μm thick. Since techniques to calculate the resistance of a corner are complex, estimate the resistance by calculating a reasonable a) lower bound and b) upper bound resistance between points A and B. Explain your reasoning.
                    40 μm
      A --+    2.4 μm wide         |
          +------------------+     |
                             |     |  3
                             |     |  0
                             |2.8μm|  μ
                             |wide |  m
                             |     |
                             |     |
                             |     +-------------+
                             |      3.2 μm wide  +-- B
                                   20 μm
  2. [60 pts] Flip-flop cell. Use the positive-edge triggered, master-slave flip-flop called the "Safest Flip-Flop" in the handout posted on the course web page. Include two inverters inside each flip-flop to buffer the single clock input and generate clock_buf and clock_bar (for internal cell use only). The clock input must drive only one inverter and no other circuits.

  3. [25 pts] Design a large buffer cell consisting of a single inverter which abuts directly to the "Q_bar" output of your flip-flop. The inverter must have a PMOS width of 75 λ and an NMOS width of 50 λ and must use folded transistors. Submit a printout of the layout for the buffer abutted to your flip-flop cell.

  4. [25 pts] A cell in magic called twelveFFs which is composed of 12 instances of the flipflop cell. Design it with inputs Vdd, Gnd, clock, in00 - in11, and outputs out00 - out11.

  5. [100 pts] Simulation. Layout a cell called top which instantiates one copy of twelveFFs and connects all FFs into one long chain by connecting the output of FF00 to the input of FF01 and so forth. No credit can be given unless the layout is complete and fully functional.

    Test top in irsim with the following pattern:

    1) Fill the FF chain with all "0"s
    2) Inject a single "1" into the chain
    3) Fill the FF chain with all "0"s (produces a "walking 1" pattern)
    4) Fill the FF chain with all "1"s
    5) Inject a single "0" into the chain
    6) Fill the FF chain with all "1"s (produces a "walking 0" pattern)
    Demonstrate the irsim waveform to your TA during lab.

2013/11/16         Posted