Programmable
Logic Devices (PLD)
•PLD chips can be erased electrically and program to implement different logic
function.
•Designing
with PLD chips is faster
which reduce time to bring the product in market.
•To
reprogram PLD we do not have to redesign circuit board.
•Simple
Programmable Logic Devices (SPLD), Complex Programmable Logic
Devices (CPLD) and Field Programmable Gate Array
(FPGA) are the types of Programmable
Logic Devices (PLD).
•SPLD includes Read Only Memory (ROM),
Programmable Logic Array (PLA), Programmable Array Logic (PAL) and
Generic Array Logic (GAL).
•FPGA and CLPD are the types of advanced PLDs.
Simple
Programmable Logic Devices
(SPLD)
•There
are three main types of SPLD architecture
Programmable Logic Array (PLA), Programmable Array Logic (PAL) and Generic Array Logic (GAL).
•SPLD
is made from macro
cell each cell made from AND-OR
structure based on the AND
array feeding
into OR array.
•PLA have four input and four output.
•PLA can not be reconfigured.
•PLA is One Time Programmable (OTP).
•PAL is simpler than PLA architecture.
•PAL have faster designing.
•PAL have have 20 to 24 pins.
•PAL have low propagation delay of
about 5
ns.
•PAL is One Time Programmable (OTP).
•PAL can not be reconfigured.
•GAL uses EEPROM configuration so it can be reconfigured.
Complex
Programmable Logic Devices
(CPLD)
•CPLDs are the collection of SPLD structures which are interconnected
via multiplexer or switch matrix.
•CPLD consists of number of logic blocks or functional blocks.
•And
each block contain PLA
or PAL.
•Using
CPLDs more complex design can be
implemented.
•Propagation
delay is about 8
ns.
•CPLD have large number of gates and can include complicated feedback path.
•CPLD are ideal for critical control
application because it offers predictable timing characteristics.
•CPLD are use in cost sensitive
application and it have low power usage.
Field Programmable Gate Array (FPGA)
Field Programmable Gate Array (FPGA)
•FPGA is field programmable gate array.
•FPGA are PLDs which are made from interconnected small macro cells.
•It is made from logic cells.
•Logic cells are connected each other by horizontal and vertical channel.
•Each logical cell is having a complicated design.
•These logic gates are made from NAND gates.
•They are thousands in number.
•You can make anything using FPGA like you can make it a microcontroller or you can make it digital signal processor or any thing.
•FPGA consist of various I/o pins.
•I/o pins connects the chip to the outside world.
•All the logic gates are connected to each other via channel these channel are made from conducting metal.
•The channels are matrix in shape.
•With FPGA it is possible to integrate multiple storage registers, arithmetic and logic circuits, controllers etc. on the same device.
•FPGA is a very flexible chip.
•FPGA is a volatile device.
•It clear everything when the power supply is removed.
•FPGA have 84 to 256 pins.
WHAT ARE FPGAs USES ?
•FPGA is use for High Performance Computing.
•FPGA is use for Digital Signal Processing (DSP).
•FPGA is use for Phase-locked loops.
•FPGA is use for Routers.
•FPGA is use for Video & Image Processing.
•FPGA is use for High-end RADARs.
•FPGA is use for Speech recognition.
•FPGA is use for ACSI prototyping.
•FPGA is use for Bioinformatics.
WHAT ARE FPGAs ADVANTAGES ?
•Make anything like DSP or Microcontroller.
•It is too fast.
•Programmable.
•Shorter time to market.
•FPGA are suitable choice for microprocessor.
•Efficient system.
•Parallel data processing.
•Update feature from customer site.
•Real time applications.
•Synthesis is easier than ASCI.
WHAT ARE FPGAs DISADVANTAGES ?
•Its cost is very high.
•Not optimize for power consumption.
•It is very complicated.
•Programming is difficult.
•Volatile.
•Large number of pins.
•Slow design software.
•Don't provide fix delay.
