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Circuit technologies Max. chapter. 3

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Circuit technologies (Max. ch. 3)

Programmable logic circuits (PLD):• Simple Programmable Logic Device (SPLD)• Complex Programmable Logic Devices (CPLD)• Field Programmable Gate Array (FPGA)

Not re-programmable logic circuits :• Application-Specific Standard Parts (ASSPs)• Application Specific Integrated Circuit (ASICs)

System On Chip (SoC)

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The following applies for all the figurescopied from the text book:

The Design Warrior’s Guide to FPGAsDevices,Tools, and Flows.

ISBN 0750676043

Copyright © 2004 Mentor Graphics Corp.(www.mentor.com)

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Circuit technologies

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Difference between a microprocessor andprogrammable logic

• A micro processor is programed withinstructions (which are stored in RAM/ROM)

• A programmable logic circuit is programed bya circuit description

• A programmable circuit consist ofconfigurable blocks of logic and configurableconnections between these block

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Random-Access Memory (RAM)

• Stored binary iformation in groups of bitscalled words

• Volatile– Stored information disappears when powered off.

• Types:– Static (flip-flops used as storage element)– Dynamic (electronic charge on capacitors stores

data)

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Programmable Read Only Memory (ROM)

• Similar organization as RAM, but different storagetechnology)

• 1 decoder (n inputs and 2n outputs) + m OR gates• Can be programmed only once• Used as start-up programs (BIOS) or simple logic.

1 decoderm OR-ports

n addresslines m word lines

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Programmable Read Only Memory

a b c

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Address 0 &

Address 1 &

Address 2 &

Address 3 &

Address 4 &

Address 5 &

Address 6 &

Address 7 &a !a b !b c !c

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!a c!b& &

!a !cb& &

!a cb& &

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a c!b& &

a !cb& &

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Predefined AND array

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ram

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w x y

Predefined linkProgrammable link

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gram

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ray

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Programmable Array Logic (PAL)

• Programmable AND-array,and fixed OR-array

• Can not share AND termsbetween different OR-terms

• Re-programmable devicesexist (GAL)

• Widely used

l l l

Pred

efin

edO

Rar

ray

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Programmable logix architeture

• Circuit with inputs, ouputs, logic, flip-flops andprogrammable connections

• Families:– SPLD - Simple Programmable Logic Device– CPLD - Complex Programmable Logic Device– FPGA - Field Programmable Gate Array– CSoC - Configurable System-on-Chip

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lse

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SPLD - Simple Programmable LogicDevice

• Characteristics:– The smallest and cheapest type of programmable logic

• Other names:– PROM (Programmable Read Only Memory)– PLA (Programmable Logic Array)– PAL (Programmable Array Logic, Vantis)– GAL (Generic Array Logic, Lattice, Lattice)

• Programming:– Fuses or non-volatile memory like EPROM, EEPROM or

FLASH.

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Example: GAL22V10 (Lattice)

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Example : GAL22V10 (Lattice)

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PLD programmer

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CPLD - Complex ProgrammableLogic Device

• Characteristics:– A typical CPLD has from 2 to 64 times more logic as a

SPLD.• Other names

– EPLD (Erasable Programmable Logic Device)– EEPLD (Electrically-Erasable Programmable Logic Device)– MAX (Multiple Array matriX, Altera)

• Programming:– Fuses or non-volatile memory like EPROM, EEPROM or

FLASH (SRAM based are also available)

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CPLD

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Example-Max3000A (Altera)

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Example-Max3000A (Altera)

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Example-Max3000A (Altera)

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FPGA - Field Programmable GateArray

• Characteristics: Offers a much more logicthan a CPLD

• Other names:– LCA (Logic Cell Array)– pASIC (programmable ASIC), Cypress– Flex, Apex, Cyclone, Arria, Stratix (Altera)– ProASIC, IGLOO (Microsemi tidl. Actel)– ORCA (Lucent)– Spartan, Virtex, Artix, Kintex (Xilinx)

• Programming: Static memory (SRAM) or anti-fuse technology (also some with EEPROM orFLASH exist)

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FPGA

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Example logical block in a FPGA

Kombinatorisklogikk

Sekvensielllogikk

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Look-Up Table (LUT)

8:1

Mul

tiple

xer

0 0

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Evolution of programmable devices

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ASIC: Application Specific IntegratedCircuit

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When to use a FPGA/CPLD?

• FPGA first choice for digital logic design withexeptions of:– Simple or time critical designs (ASIC/PAL/discrete

logic better)– Large volume products (ASIC better)– Very complex designs (ASIC)– Mobile applications where power consumption is

of great consern• ASIC vs FPGA

– 1500 – 4000 new ASIC projects each year– 450 000 new FPGA projects each year

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Benefits by using a FPGA vs. ASIC

• Shorter developement time due to simple re-programming

• Can be re-programmed in system out in thefield

• Much less economical risk (an ASIC isexpensive to produce and it can not be re-programmed)

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Power consumption ASIC vs FPGA(example)

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