Mumbai University > COMPS > Sem 3 > Digital Logic Design and Analysis

Marks: 10 M

Year: Dec 2013

• FPGA stands for Field Programmable Gate Array and has been developed to increase the effective size and to add more functionality in a single programmable device. The FPGAs do not contain AND, OR planes, instead they provide logic blocks for implementation of the required digital functions.
• An FPGA is composed of number of relatively independent configurable logic blocks (CLBs), configurable I/O blocks, and programmable interconnection paths known as routing channels.
• All the resources of the device are uncommitted and that these must be selected, configured and interconnected by a user to form a logic circuit for this application.
• The basic architecture of an FPGA is shown below:

• The basic architecture consists of an array of configurable logic blocks. The logic blocks are surrounded by configurable I.O blocks. The I/O blocks can be individually configured as input, output or bidirectional.
• There are rows and columns of programmable interconnection paths. The common row/column interconnects are known as global interconnects.
• A logic block consists of a number of logic modules. The logic modules are basic elements in an FPGA. The logic modules within a CLB are connected through local programmable interconnects.
• A logic module consists of a Look up table, D-Flip Flop and a multiplexer. An Look-up table consists of a programmable memory and is used to generate a logic function in SOP form.
• There are a number of manufacturers of FPGA devices. The various families of FPGAs manufactured by different manufacturers differ primarily in a number of logic modules, supply voltage range, power consumption, speed, etc.

• Advantages:

  1. High logic density

  2. Flexible

  3. Logic blocks are small in size compared to CPLD