Digital VLSI Design and FPGA Implementation

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  • 1.Digital VLSI Design & FPGA ImplementationPrepared by : AMBER BHAUMIK

2. About The Training Objective The Program emphasizes on imparting overall exposure to the concept and design methodologies of all major aspects of VLSI engineering relevant to the industry's needs. Program offers in-depth hands-on training on various design methodologies used in industries. The course is comprehensive and rigorous, enabling the student to quickly ramp up to the level of real-world project readiness thus enhancing his/ her career prospects in the industry.Training Contents VLSI Fundamentals & Digital Design Introduction to VHDL Overview of HDL-Based Design Getting Started Design Description Design Entry Synthesizing the Design Behavioral Simulation FPGA ImplementationLab Work The Labs for this training provides a practical foundation for creating synthesizable RTL code. All aspects of the design flow are covered in the labs. The labs are written, synthesized, simulated and implemented by the student. Student will simulate some good applications. After Completing this training: Student will be ready to design any digital design using VHDL. 3. WHAT IS VLSI ? VLSI is the short-form for Very-large-scale integration, a process that means to create integrated circuits by combining thousands of transistor-based circuits into a single chip. VLSI finds immediate application in DSP, Communications, Microwave and RF, MEMS,Cryptography, Consumer Electronics, Automobiles, Space Applications, Robotics, and Health industry. Nearly all modern chips employ VLSI architectures, or ULSI (ultra large scale integration). The line that demarcates VLSI from ULSI is very thin.SCOPE OF VLSI There is a rising demand for chip driven products in consumer electronics, medical electronics, communication, aero-space, computers etc. More and more chip designing companies have set up their units in India eying on the Indian talents; besides many of the Indian Major IT companies have forayed in Application Specific Integrated Circuit (ASIC) design in a big way. With the design & manufacturing market (both domestic & international) expanding rapidly, there is an enhanced demand of trained professionals who will boost the technical work force in the VLSI domain. 4. What is an FPGA? A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by the customer or designer after manufacturinghence "field-programmable". The FPGA configuration is generally specified using a hardware description language (HDL), FPGAs can be used to implement any logical function that an ASIC could perform. The FPGA is an integrated circuit that contains many (64 to over 10,000) identical logic cells that can be viewed as standard components. Eachlogic cell can independentlytake on any one ofa limited set ofpersonalities. The individual cells are interconnected by a matrix ofBlock RAMsBlock RAMswires and programmable switches. A user's design is implemented by specifying the simple logic function for each cell and selectively closing the switches in the interconnect matrix. The array of logic cells and interconnect form a fabric of basic building blocksfor logiccircuits. Complex designs are created by combining these basic blocks to create the desired circuit. Implementation includes many phasesConfigurable Logic BlocksI/O BlocksBlock RAMs Translate : Merge multiple design files into a single netlist Map : Group Logical symbols from the netlist (Gates) into physical components (CLB s and IOBs ) Place & Route : Place components onto the chip, connect them and extracts timing data into reports Timing (Sim) : Generate a back annotated netlist for timing simulation tools Configure : Generate a bit stream for device configuration 5. Introduction to VLSI, IC History, EDA ToolsModule -I ( 1st Week)About VLSI VLSI is the field which involves packing more and more logic devices into smaller and smaller areas. Thanks to VLSI, circuits that would have taken boardfuls of space can now be put into a small space few millimetres across! This has opened up a big opportunity to do things that were not possible before. VLSI circuits are everywhere ... your computer, your car, your brand new state-of-the-art digital camera, the cell-phones, and what have you. All this involves a lot of expertise on many fronts within the same field, which we will look at in later sections. Integrated Circuits (Chips) Integrated circuits consist of: -- A small square or rectangular die, < 1mm thick Small die: 1.5 mm x 1.5 mm => 2.25 mm2 Large die: 15 mm x 15 mm => 225 mm2 -- Larger die sizes mean: More logic, memory Less volume Less yield -- Dies are made from silicon (substrate) Substrate provides mechanical support and electrical common point IC History in terms of number of Transistors SSI Small-Scale Integration (0-102) MSI Medium-Scale Integration (102-103) LSI Large-Scale Integration (103-105) VLSI Very Large-Scale Integration (105-107) ULSI Ultra Large-Scale Integration (>=107) 6. Introduction to VLSI, IC History, EDA ToolsModule -I ( 1st Week)Integration Level Trends The figure shows that every 2 years the number of components on an area of silicon(chip) doubled, which is called Moores Law.Obligatory historical Moores law plotElectronic design automation (EDA)- Set of software tools used for VLSI chip design. EDA Tool Categories: 2. Bases on Design Flows 1. Based on design methodology Full Custom Design Standard Cell Based Design FPGA Design Structured ASIC Design Implementation Tools Logic and Physical Synthesis Full Custom Layout Floor Planning Place & Route Verification Tools Simulation Timing Analysis Formal verification Power analysis Signal integrity DRC and LVS 7. Basics of Digital DesignModule -I ( 1st Week)From transistors to chips Chips from the bottom up: 1) Basic building block: the transistor = on/off switch 2) Digital signals voltage levels high/low 3) Transistors are used to build logic gates 4) Logic gates make up functional and control units 5) Microprocessors contain several functional and control units This section provides an introduction into digital logic 1) Combinatorial and sequential logic 2) Boolean algebra and truth tables. 3) Basic logic circuits. 4) Decoders, multiplexers, latches, flip-flops. 5) Simple register design. Boolean expressions Uses Boolean algebra, a mathematical notation for expressing two-valued logic Logic diagrams A graphical representation of a circuit; each gate has its own symbol. Logic blocks are categorized as one of two types, depending on whether they contain memory. Blocks without memory are called combinational; the output of a combinational block depends only on the current input. In blocks with memory, the outputs can depend on both the inputs and the value stored in memory, which is called the state of the logic block. Truth tables A table showing all possible input value and the associated output values. Truth tables can completely describe any combinational logic function; how- ever, they grow in size quickly and may not be easy to understand. Sometimes we want to construct a logic function that will be 0 for many input combinations, and we use a shorthand of specifying only the truth table entries for the nonzero out- puts. 8. Basics of Digital Design Six types of gates NOT , AND , OR, XOR, NAND, NOR NOT Gate A NOT gate accepts one input signal (0 or 1) and returns the opposite signal as outputAND Gate An AND gate accepts two input signals If both are 1, the output is 1; otherwise, the output is 0OR Gate An OR gate accepts two input signals. If both are 0, the output is 0; otherwise, the output is 1Module -I ( 1st Week) 9. Basics of Digital DesignModule -I ( 1st Week)XOR Gate An XOR gate accepts two input signals If both are the same, the output is 0; otherwise, the output is 1The difference between the XOR gate and the OR gate; they differ only in one input situation. When both input signals are 1, the OR gate produces a 1 and the XOR produces a 0. XOR is called the exclusive OR. NAND Gate The NAND gate accepts two input signals, If both are 1, the output is 0; otherwise, the output is 1NOR Gate The NOR gate accepts two input signals If both are 0, the output is 1; otherwise, the output is 0 10. Basics of Digital Design Combinational circuit The input values explicitly determine the output. Gates are combined into circuits by using the output of one gate as the input for another.Three inputs require eight rows to describe all possible input combinations. This same circuit using a Boolean expression is (AB + AC). Circuit equivalence Two circuits that produce the same output for identical input. Boolean algebra allows us to apply provable mathematical principles to help design circuits. A(B + C) = AB + BC (distributive law) so circuits must be equivalent.Module -I ( 1st Week) 11. Basics of Digital DesignModule -I ( 1st Week)Properties of Boolean AlgebraAdders At the digital logic level, addition is performed in binary Addition operations are carried out by special circuits called, appropriately, adders. The result of adding two binary digits could produce a carry value Recall that 1 + 1 = 10 in base two . Half adder A circuit that computes the sum of two bits and produces the correct carry bit Boolean expressions sum = A B carry = AB 12. Basics of Digital Design Full adder A circuit that takes the carry-in value into accountBasic Laws of Boolean Algebra Identity laws: A + 0 = A A*1=A Inverse laws: A + A = 1 A*A=0 Zero and one laws: A + 1 = 1 A*0=0 Commutative laws: A + B = B+A A*B=B*A Associative laws: A + (B + C) = (A + B) + C A * (B * C) = (A * B) * C Distributive laws : A * (B + C) = (A * B) + (A * C) A + (B * C) = (A + B) * (A + C)Module -I ( 1st Week) 13. Basics of Digital DesignModule -I ( 1st Week)Sequential circuit The output is a function of the input values and the existing state of the circuit We describe the circui