Fpga intro1
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Fpga intro1 Fpga intro1 Presentation Transcript

  • Presented by :Srishti Jain (cs - A) V sem
  • FPGA :- A Field Programmable Gate Array (FPGA) is a Programmable Logic Device(PLD) with higher densities and capable of implementing different functions in a short period of time. Topics covered:- • FPGA Overview • FPGA in detail • Programming Methodology
  • FPGA overview 2-D array of logic blocks and flip-flops with programmable interconnections. Compact design User can configure  Intersections between the logic blocks  The function of each block
  • FPGA in detail: Logic blocks:  has an undefined function at the time of manufacture. before use, it must be programmed (i. e. reconfigured).  Contains-  Look-Up-Table(LUT)  Multiplexer  Flip-flop  Can be programmed to function as  Transistor  Microprocessor  Any combination of combinational and sequential logic functions to be continue..
  •  INTER CONNECTIONS  Are electrically programmable interconnection between the logic blocks.  Also contains electrically programmable switches.  A hierarchy of interconnect allows logic blocks to be interconnected as per system designer. Like one chip programmable breadboard.
  • Programming Methodology Electrically programmable switches are used to program FPGA Properties of programmable switch determine on- resistance, parasitic capacitance, volatility, reprogrammability, size etc. Desired properties:  Minimum area consumption  Low on resistance; High off resistance  Low parasitic capacitance to the attached wire  Reliability in volume production Various programming techniques are:-  SRAM programming technology  Antifuse programming technology  EPROM /EEPROM programming technology
  • SRAM ProgrammingTechnology Employs SRAM (Static RAM) cells to control pass transistors and/or transmission gates SRAM cells control the configuration of logic block as well Volatile  Needs an external storage  Needs a power-on configuration mechanism  In-circuit re-programmable Lesser configuration time Occupies relatively larger area
  • Anti-fuse ProgrammingTechnology Though implementation differ, all anti-fuse programming elements share common property  Uses materials which normally resides in high impedance state  But can be fused irreversibly into low impedance state by applying high voltage
  •  Very low ON Resistance (Faster implementation of circuits) Limited size of anti-fuse elements; Interconnects occupy relatively lesser area  Offset : Larger transistors needed for programming One Time Programmable  Cannot be re-programmed  (Design changes are not possible)  Retain configuration after power off
  • EPROM Programming Technology  EPROM Programming Technology  Two gates: Floating and Select  Normal mode:  No charge on floating gate  Transistor behaves as normal n-channel transistor  Floating gate charged by applying high voltage  Threshold of transistor (as seen by gate) increases  Transistor turned off permanently  Re-programmable by exposing to UV radiation
  • EPROM transistorEPROM memory cell
  •  No external storage mechanism Re-programmable (Not all!) Not in-system re-programmable Re-programming is a time consuming task An EPROM cell is erased by discharging the electrons on that cell’s floating gate. The energy required to discharge the electrons is provided by a source of ultraviolet (UV) radiation.
  • EEPROM ProgrammingTechnology Two gates: Floating and Select Functionally equivalent to EPROM; Construction and structure differ Electrically Erasable: Re-programmable by applying high voltage (No UV radiation expose!) When un-programmed, the threshold (as seen by select gate) is negative!
  • summary
  • Other FPGA Advantages Manufacturing cycle for ASIC is very costly, lengthy and engages lots of manpower Mistakes not detected at design time have large impact on development time and cost FPGAs are perfect for rapid prototyping of digital circuits Easy upgrades like in case of software Unique applications
  • Why better ? FPGA programmed using electrically programmable switches Routing architectures are complex. Logic is implemented using multiple levels of lower fan-in gates. Shorter time to market Ability to re-program in the field to fix bugs FPGA DISADVANTAGE FPGAs are generally slower than their application- specific integrated circuit (ASIC) Cant handle as complex a design, and draw more power.
  • Application Reconfigurable computing. Applications of FPGAs include DSP, software-defined radio. The inherent parallelism of the logic resources on the FPGA allows for considerable compute throughput.
  • FPGA Design and Programming To define the behavior of the FPGA the user provides a hardware description language (HDL) or a schematic design. Then, using an electronic design automation tool, a technology- mapped net list is generated. The netlist can then be fitted to the actual FPGA architecture using a process called place-and-route. The user will validate the map, place and route results via timing analysis, simulation, and other verification methodologies. Once the design and validation process is complete, the binary file generated used to configure the FPGA.