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CSE45435 – VLSI Design

CSE45435 – VLSI Design. Lecture #2 Please note the change in Office Hours Office hours: Monday 3.00 - 5.00 Tuesday 11.30 - 1.00. Trends in Microprocessor Technology. Evolution in Complexity. Silicon in 2010. Die Area: 2.5x2.5cm Voltage: 0.6 V Technology: 0.07  m.

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CSE45435 – VLSI Design

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  1. CSE45435 – VLSI Design Lecture #2 Please note the change in Office Hours Office hours: Monday 3.00 - 5.00 Tuesday 11.30 - 1.00 Lecture #2

  2. Trends in Microprocessor Technology Lecture #2

  3. Lecture #2

  4. Lecture #2

  5. Evolution in Complexity Lecture #2

  6. Silicon in 2010 Die Area: 2.5x2.5cm Voltage: 0.6 V Technology: 0.07m Lecture #2

  7. WHY MONOLITHIC INTEGRATION OF A LARGE NUMBER OF FUNCTIONS ON A SINGLE CHIP? • Demand for higher computing power • Low cost • Small size • More circuitry  more transistors • Dense packing requirement with limited die size (less than 1.5cm on a side) Lecture #2

  8. Why build integrated Circuit? • IC Technology is driving the whole innovative devices and systems which effected the way we live. Print a circuit, like printing a picture • ICs are much smaller • consume less power than discrete component • easier to design and manufacture • more reliable than discrete system • can design more complex system • cost no longer dependent on # of devices • Fast growth of electronic industry. Lecture #2

  9. VLSI applications • Electronic system in cars • Digital electronics control VCRs • Transaction processing system, ATM • Personal computers and Workstations • Medical electronic systems • Laptops, cellphones, PDAs • etc…. Lecture #2

  10. The advantages of digital ICs over discrete components • Size • much smaller both transistor and wires. • leads to smaller parasitic resistances, capacitances and inductances • Speed • communication within the chips are much faster than between the chips on a PCB • High speed of circuits on-chip due to smaller size • Power Consumption • Logic operation within the chip consumes much less power • Smaller size --> smaller parasitic capacitances and resistance --> require less power to drive the circuit Lecture #2

  11. Advantages of IC at System Level • Smaller Physical Size • can make small electronic appliances. ie. PortableTV, handheld cellular telephone… • Lower Power Consumption • reduces total power consumption of a whole electronic circuit. • cheaper power supply which leads to a simpler cabinet for power supply. Less heat, cooling fans may no longer be necessary. Lecture #2

  12. Advantages of IC at System Level (cont.) • Reduced Cost • Reduction in number of components. • Power Supply requirement. • Cabinets • The cost of building a whole system is reduced eventhough ICs cost more. Lecture #2

  13. Integrated Circuit Manufacturing Technology • Select technology to build a complex system in the fastest possible way. Economics • IC plant is very expensive. $1billion or more. • Is it worth to invest in IC business? Lecture #2

  14. Moore’s Law In 1960s,Gordon Moore: Co-founder of INTELpredicted that the number of transistors would grow exponentially (Double every 18 months). Exponential improvement in technology is a natural trend: steam engines, dynamos, automobiles etc. ln (#dev) good year Lecture #2

  15. Good News Since the cost of the printing process (called wafer fabrication) was growing at a modest rate, it implied that the cost per function was dropping exponentially. At each new generation, each gate costs about 1/2 what it did 3 years ago. Shrinking an existing chip makes it cheaper! ln(cost/function) die cost year year Lecture #2

  16. Bad News • Although the cost of manufacturing IC's remained approximately constant, the design cost did not. In fact, while designer productivity has improved with time, it has not increased at the same rate as the complexity of the chips. • So the cost of the chip design is growing exponentially with the complexity of the circuit. Integrating a system on a piece of silicon has an attractive manufacturing cost, but frightening design cost and risk. Need to build very complex stuff. • In addition, the number of custom IC designers was (and is) fairly limited. Even if you were willing to take the risk, where would you find the people to do the design? ln(design cost/function) y ear ln(design cost) y ear Lecture #2

  17. Custom Performance Std Cell Gate Array FPGA Cost Design Technology Lecture #2

  18. VLSI Technology 1. Schottky TTL (Transistor-transistor logic) Lecture #2

  19. VLSI Technology 2. ECL (Emitter coupled logic) NOR Lecture #2

  20. VLSI Technology 3. MOS (Metal Oxide semiconductor) NOR Lecture #2

  21. VLSI Technology 4. CMOS (Complementary MOS) NOR Lecture #2

  22. Most Prominent Technology - CMOS Smaller sized transistors   Lower power consumption Zero static power   Dynamic power increases with switching But SLOW compared to others Compromise - BiCMOS Technology Lecture #2

  23. Manufacturing Steps 1.  Circuit schematic - transistor circuit diagram 2.  Layout generation - rectangular patterns for transistors and interconnect 3. Mask generation 4. Chip fabrication Lecture #2

  24. Challenges faced Defects in wafer ·    use minimum die area Reduce cost ·    use minimal layout area Increase speed ·    use efficient interconnect patterns – ( long and winding paths reduce speed) Short design time High market competition Lecture #2

  25. Digital abstraction signals are 1 or 0 Switch abstraction MOSFETs as simple switches Gate abstraction Unidirectional elements Separable timing Synchronous abstraction Race free logic Function does not depend on timing Partition the problem (Use hierarchy) Module is a box with pins apply recursively Abstractions and Disciplines How to Deal with 109 Transistors? Lecture #2

  26. Design Abstraction Levels Lecture #2

  27. What is on an Integrated Circuit? • Actually only two types of things: • Conducting layers which form the wires on the IC. • There are many layers of wires (used to have 1 layer of metal, now advanced processes have 5-7 metal layers). Wires have electrical properties like resistance and capacitance. • (Requires insulators and contacts between layers.) • Transistors (the free things that fit under the wires). • There are a few kinds of transistors. In this course we will study MOS ICs, so we will work with MOS transistors. These transistors can be thought of as voltage controlled switches. The voltage on one terminal of the transistor determines whether the other two terminals are connected or not. Lecture #2

  28. MOSFET Fundamentals N-channel Metal Oxide Semiconductor Field-Effect Transistor NMOS Transistor Lecture #2

  29. + + + + + + + + + + + + + + + + + + + + The MOS Capacitor Negative Voltage To Metal Lecture #2

  30. + + + + + + + + + + + + + + + + + + + + The MOS Capacitor Small Positive Voltage To Metal Lecture #2

  31. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + The MOS Capacitor Less Positive More Positive Much More Positive n n << Ions V < VT n >> Ions V > VT n Ions V  VT VT Minimum Voltage for Inversion Lecture #2

  32. NMOS Transistor Lecture #2

  33. PMOS Transistor Lecture #2

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