Complex Programmable Logic Devices(CPLD) & Field Programmable Logic Devices (FPGA)
- 1. Contents: Introduction Architecture Comparison between CPLD & FPGA Kongunadu College of Engineering & Technology CPLD & FPGA 1
- 2. It is merely a collection of multiple PLDs and an interconnection structure, all on the same chip. In addition to individual PLDs, the on-chip interconnection structure is also programmable. 2Kongunadu College of Engineering & Technology CPLD & FPGA
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- 5. It consists of collection of PAL like blocks, I/O blocks and a set of interconnection wires, called programmable interconnection structure. The PAL like blocks are connected to the programmable interconnect structure and to the I/O blocks and it usually consists of 16 macrocells. The macrocells in CPLD consists of AND-OR configuration, an EX-OR gate, a flip-flop, a multiplexer and a tri-state buffer. The EX-OR gate provides the output of OR-gate in inverted or non-inverted form as per the fuse link status. A D flip flop stores the output of EX-OR gate. Multiplexer selects either the output of the D flip flop or the output of the EX-OR gate depending on the select input. The tri-state buffer acts as a switch which enables or disables the output. 5Kongunadu College of Engineering & Technology CPLD & FPGA
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- 7. The word field refers to the ability of the gate arrays to be programmed for the specific function by the user instead of by the manufacturer of the device. The word array is used to indicate the series of columns and rows of gates that can be programmed by the end user. The programmable logic blocks of FPGAs are called logic blocks or configurable logic blocks(CLBs). 7Kongunadu College of Engineering & Technology CPLD & FPGA
- 8. The basic structure of FPGA consists of an array of logic blocks with programmable row and column interconnecting channels surrounded by programmable I/O blocks. Look-up table(LUT) is used as a memory device that can be programmed to perform logic functions. Each logic block in a generic FPGA contains several logic elements. The logic element consists of LUT, associated logic and a flip-flop. 8Kongunadu College of Engineering & Technology CPLD & FPGA
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- 11. FPGA CPLD Consists of configurable logic blocks, I/O blocks, row interconnect and column interconnect. Consists of PAL like blocks, I/O blocks and programmable interconnect structures. They use memory called LUT or multiplexers to generate logic functions. They use AND/OR arrays to generate logic functions. They are programmed for specific function by the user. They are programmed for specific function by the manufacture of the device. More complex architecture. Less complex architecture. Delays are quite unpredictable. Delays are more predictable. It is more expensive It is much cheaper FPGAs are made up of tiny logic blocks. CPLDs are made of larger blocks. 11Kongunadu College of Engineering & Technology CPLD & FPGA
- 12. Conclusion: The architecture of CPLD and FPGA has been discussed and their comparison has been listed. References: Mandal, “Digital Electronics Principles & Application, McGraw Hill Edu, 2013. William Keitz, Digital Electronics-A Practical Approach with VHDL, Pearson, 2013. Thomas L.Floyd, ‘Digital Fundamentals’, 11th edition, Pearson Education, 2015. Charles H.Roth, Jr, Lizy Lizy Kurian John, ‘Digital System Design using VHDL, Cengage,2013. D.P.Kothari,J.S.Dhillon, ‘Digital circuits and Design’,Pearson Education, 2016. A.P.Godse., Dr.D.A.Godse, ‘Digital Logic Circuits’ , Technical Publications Third Edition 2016 Other Web Sources 12Kongunadu College of Engineering & Technology CPLD & FPGA