VLSI复习题型：缩写5题10分简答12题60分计算3题30分Chapter 011.How to evaluate performance•Cost•Reliability•Speed (delay, operating frequency)•Power dissipation2.Regenerative property3.Delay :Chapter 021.Inverter layout2.Photolithography process1)Oxidation layering(氧化层)2)Pthotoresist coating（涂光刻胶）3)Stepper exposure（光刻机曝光）4)Photoresist development and bake(光刻胶的显影和烘干)5)Acid etching（酸刻蚀）6)Spin, rinse, and dry（旋转，清洗和干燥）7)Various process steps：Ion implantation（离子注入）Plasma etching（等离子刻蚀）Metal deposition（金属沉淀）8)Photoresist removal( or ashing) 去除光刻胶（即“沙洗”）Chapter 031.Linear/ Saturation mode2.Long channel vs short channel3.Capacitances= structure capacitances+channel capacitances+MOS diffusion capacitances4.Resistance=MOS sructure resistance+source and drain resistance+cantact resistance+wiringresistanceWith silicidation R方块ˆ is reduced to the range 1 to 4 Ω/方块（source and drain resistance）Chapter 041.C wire = C pp + C fringe + C interwire2.Dealing with resistance:1)Use better interconnect materials2)More interconnect layers3.RC Mode•Lumped RC model–total wire resistance is lumped into a single R and total capacitance into a single C–good for short wires; pessimistic and inaccurate for long wires•Distributed RC model–circuit parasitics are distributed along the length, L, of the wire4.DelayDelay of a wire is a quadratic function of its length, LThe delay is 1/2 of that predicted (by the lumped model)5.Reflection coefficient【画传输图（or 波形），计算题】Chapter 051.V M∝(W/L)p/(W/L)nIncreasing the width of the PMOS moves V M towards V DD,‰Increasing the width of theNMOS moves V M towards GND.2.Delay3.Power in CMOS1.Dynamic power consumption: charging and discharging capacitors;Not a function of transistor sizes;Need to reduce C L,Vdd,and f to reduce power.2.Short circuit currents: short circuit path supply rails during switching;Keep the input and output rise/fall times the same;If Vdd<Vtn+|Vtp|,then short-circuit power can be eliminated.3.Leakage: leaking diodes and transistors4.Technology scaling modelsFull scalingFixed voltage scalingGeneral scalingChapter 061.Static CMOS- output connected to either Vdd or GND via a low-resistance path⏹High noise margins⏹Low output impedance, high input impedance⏹No steady state path between Vdd and GND⏹Delay is a function of load capacitance and transistor resistanceDynamic CMOS--relies on temporary storage of signal values on capacitance of high-impedance circuit nodes.⏹Simpler, faster gates⏹Increased sensitivity to noise2.Static vs dynamic circuit⏹In static circuit at every point in time (except when switching) the output is connectedto either GND or V DD via a low resistance path.--fan-in of N requires 2N devices⏹Dynamic circuits rely on the temporary storage of signal values on the capacitance ofhigh impedance nodes--requires only N+2 transistors--takes a sequence of precharge and conditional evaluation phases to realize logicfunctions.●conditions on output1) once the optput of a dynamic gate is discharged, it cannot be charged again until thenext precharge opreation.2) Inputs to the gate can make at most one transition during evaluation.3) Output can be in the high impedance state during and after evaluation(PDN off), stateis stored in C L.●Properties of Dynamic Gates1)Logic function is implemented by the PDN only–number of transistors is N + 2 (versus 2N for static complementary CMOS)–should be smaller in area than static complementary CMOS2)Full swing outputs (VOL = GND and VOH = VDD)3)Nonratioed--sizing of the devices is not important for proper functioning (only for performance)4) Faster switching speeds5) Power dissipation should be better- consumes only dynamic power –no short circuit power consumption since the pull- up path is not on when evaluating-lower C L--both C int(since there are fewer transistors connected to the drain outpu t) and C ext(since there the output load is one per connectedgate, not two) -by construction can have at most one transition per cycle – no glitching6) Needs a percharge clockbinational vs Sequential logic4.Why PMOS in PUN and NMOS in PDN?Threshold drops5.Ratioed logic: Pseudo-NMOS→Small area and load, but static power dissipationChapter 07tch vs Register⏹Latch: level sensitive----As for positive: passes inputs to Q when the clock is high----transparent mode;When clock is low----hold mode⏹Flip-flop: edge sensitive2.Bistable circuit:The cross coupling of two inverters results in a bistablecircuit (a circuit with two stable states)⏹Have to be able to change the stored value by making A (or B) temporarily unstable byincreasing the loop gain to a value larger than 1Done by applying a trigger pulse at Vi1 or Vi2the width of the trigger pulse need be only a little larger than the total propagation delayaround the loop circuit (twice the delay of an inverter)⏹Two approaches used1.cutting the feedback loop (mux based latch)2.overpowering the feedback loop (as used in SRAMs)3.MS ET timing properties⏹Set-up time: time before rising edge of clk that D must be valid⏹Propagation delay: time for QM to reach Q⏹Hold time: time D must be stable after rising edge of clk4.Pipelining5.Schmitt Trigger(rise—P; fall—N)Chapter 091.Cross Talk: An unwanted coupling from a neighboring signal wire to a network nodeintroduces an interference that is generally called cross talk.2.Dealing with Capacitive Cross Talk•Avoid floating nodes•Protect sensitive nodes•Make rise and fall times as large as possible•Differential signaling•Do not run wires together for a long distance•Use shielding wires•Use shielding layers3.Cross Talk and Performance: when neighboring lines switch in opposite direction of victimline, delay increases.4.Impact of resistance is commonly seen in power supply distribution:–IR drop–Voltage variationsChapter 101.Clock Nonidealities:⏹Clock skew: Spatial variation in temporally equivalent clock edges;⏹Clock jitter: Temporal variations in consecutive edges of the clock signal⏹Variation of the pulse width2.Clock Uncertainties----Source of clock uncertainty（图形填空）（重点）简答题：•Clock‐Signal Generation (1)•Manufacturing Device Variations (2)•Interconnect Variations (3)•Environmental Variations (4 and 5)•Capacitive Coupling (6 and 7)3.Impact of Positive/Negative Clock Skew and Clock jitter (重点)1.Positive clock skew:Clock and data flow in the same direction2.Negative clock skew: Clock and data flow in opposite directions3.Jitter cause T to vary on a cycle-by-cycle basisCombined impact of skew and jitter:Constraints on the minimum clock period (positive)4.To reduce dynamic power, the clock network must support clock gating (shutting down(disabling the clock ) units)5. Clock distribution techniques--Balanced paths(H-tree network, matched RC trees)--Clock grids: minimize absolute delay6.Matched RC trees, represents a floor plan that distributes the clock signal so that the interconnections carrying the clock signals to the functional subblocks are of equal length.7. 彩图9：The unbalanced load creates a large skew, by careful tuning of the wire width, the load is balanced, minimizing the skew.8. Dealing with Clock Skew and Jitter•To minimize skew, balance clock paths using H-treeor matched-tree clock distribution structures. •If possible, route data and clock in opposite directions;eliminates races at the cost of performance.•The use of gated clocks to help with dynamic power consumption make jitter worse.•Shield clock wires (route power lines –VDD or GND –next to clock lines) to minimize/eliminate coupling with neighboring signal nets.•Use dummy fills to reduce skew by reducing variations in interconnect capacitances dueto interlayer dielectric thickness variations.•Beware of temperature and supply rail variations and their effects on skew and jitter. •Power supply noise fundamentally limits the performance of clock networks.Chapter 111.Full adder(P=A+B)2.Static vs dynamic Manchester Carry ChainStatic dynamic3.Square Root Carry Select Adder (PPT 24)4.Wallace‐Tree Multiplier(PPT 32)5.Logarithmic ShifterChapter 121.Semiconductor Memory Classification2.Bit line & word line3.Memory Timing(DRAM vs SRAM)DRAM: Multiplexde AddressingSRAM: Self-timed Address Switching/Changing 4.MOS OR ROM5. SRAM vs DRAM6. DRAM Timing7. SRAM ATD(Address Transition Detection)Chapter 131.Two Important Test Properties•Controllability ‐measures the ease of bringing anode to a given condition using only the input pins•Observability ‐measures the ease of observing thevalue of a node at the output pins2.Test Approaches•Ad‐hoc testing•Scan based test•Self test3.Scan Register11。