Programmable Hardware - An overview of FPGA

1. Programmable Hardware
An Overview
S.Yousuf Imam
TU Chemnitz

2. Agenda
 Introduction
 Logic Devices
 Programmable Logic Devices
 PLA
 PAL
 Field Programmable Gate Array(FPGA)
 Architecture
 SRAM-based/Flash-based FPGA
 Advantages and Limitations of FPGA
 Application of FPGA
 Current Market Scenarios

3. INTRODUCTION
In the world of digital electronic systems, mostly there are three
basic kinds of devices:
• Memory
• Microprocessor
• Logic Devices

4. LOGIC DEVICES
A logic device is one which can perform any logic function
Logic devices are broadly classified into two Categories:
Fixed
 Circuits in a fixed Logic Device are permanent.
 Perform one function or set of functions.
 The functionality cannot be changed after manufacturing.
Programmable
 Standard devices offer a wide range of logic features
 The functionality can be changed anytime to perform various logic function

5. PROGRAMMABLE LOGIC DEVICES
 ICs with internal logic gates and interconnects
 The term Programmable means changing hardware configuration of an internal logic
and interconnects.
 These devices allow the end user to specify the logical operation of the device
through a process called “programming”.

6. Types of PLDs
Among the several types of commercial PLDs available, there are two important types:
 PLA (Programmable logic array)
Introduced in the year 1970 by Texas Instruments.
Electronic component used to build reconfigurable circuits.
 PAL (Programmable array logic)
Introduced in the year 1978 by MMI (Monolithic Memories Inc) .

7. Programmable Logic Array(PLA)
 The PLA was developed in the middle 1970s as the first non memory programmable
logic device.
 Programmable AND array as well as programmable OR array
 Logic functions can be realized using SOP

8. Advantages and Disadvantages of PLAs
Advantages
 The architecture of PLA is more flexible.
 Frequently used in state machine design.
Disadvantages
 Complexity of Programmable Switches
 Speed Performance

9. Programmable Array Logic (PAL)
 Introduced in the year 1978 by MMI (Monolithic Memories Inc)
 Programmable AND plane, but Fixed OR plane

10. Advantages and Disadvantages of PALs
Advantages
 Frequently used in practical applications.
 Less expensive and offer better performance than PLA.
Disadvantages
 Limited inputs to the OR gates.

11. Field Programmable Logic Devices
To retain the advantages and to overcome the disadvantages of PLAS and PALS the
newly introduced devices are known as FPGAs
What do they do?
 These are reprogrammable(re-configurable) logic devices .
 Designers use software to develop any digital circuit they like and they configure
the chip to perform the function
 They are very fast– much faster than a microcontroller.

12. FPGAs
A field programmable gate array (FPGA) is a Programmable Logic
Device(PLD) with higher densities and capable of implementing different
functions in a short periodof time.

13. A simple modern architecture of FPGA

14. Architecture of FPGA
Elements of FPGA
Basic elements of an Field Programmable Gate Array are:
 CLB (Configurable Logic Block) includes digital logic, inputs, outputs.
 Interconnects provide connection between the logic blocks to implement the user
logic.
 PSM (Programmable Switch Matrix) provides switching between interconnects.
 I/O Pads used for the outside world to communicate with different applications.

15. FPGA Logic Block

16. Configuring Look-Up Table (LUT)
a
b
c
y
y a b c  
a b c y
0 0 0 1
0 0 1 0
0 1 0 1
0 1 1 1
1 0 0 1
1 0 1 0
1 1 0 1
1 1 1 1
Required Function Truth Table Programmed LUT
1
0
1
1
1
0
1
1
MUX y
a,b,c
LUT
The contents of LUT are programmed at power up

17. FPGA Implementation Technologies
 FPGA (Field Programmable Gate Array) is an integrated circuit containing gate matrix
which can be programmed by the user “in the field”.
 Configuration bitstream can be stored in FPGA using various technologies.
 Eg: SRAM based FPGA, Flash based FPGA , Antifuse based FPGA
 The majority of FPGAs is based on SRAM (Static RAM).

18. SRAM - FPGA
 SRAM-based FPGA stores logic cells configuration data in the static memory.
 Since SRAM is volatile and can't keep data without power source, such FPGAs must
be programmed (configured) upon start.
 There are two basic modes of programming:
 • Master mode – Reads configuration from External source.
 • Slave mode – Configured by an External master device.
SRAM-based FPGAs include most chips of Xilinx Virtex and Spartan families

19. Flash based - FPGA
 Flash-based FPGA uses flash as a primary resource for configuration storage
 This technology has an advantage of being less power consumptive
 Flash-based FPGAs are also more tolerant to radiation effects
Flash-based FPGA families such as Igloo and ProASIC3 are manufactured by Actel.

20. Advantages of FPGA
 High Gate Density as compared to microcontrollers.
 Super Fast as compared to ARM processors
 Massively Parallel
 High I/O Count as compared to microcontroller.
 Field Programmable-Reprogram ability

21. Limitations of FPGA
 It is Expensive as compared to ASIC chip.
 High Power consumption as compared to Low power processor or
microcontroller.
 Volatile in nature.

22. Application of FPGA

23. Current Market of FPGA
 Expected to be valued at $9.50 billion by 2023 from 5.83 billion in 2017
 Telecommunication held the largest size of FPGA market in 2016.
 Key players in FPGA market – Xilinx(US) Intel(US) Lattice Semiconductor
(US) United Microelectronics (Taiwan)
However , the inability of FPGA to substitute for ASIC devices is still the major
challenge in the market.
http://www.rnrmarketresearch.com/global-and-chinese-field-programmable-gate-
arrays-fpga-industry-2018-market-research-report-market-report.html

24. Questions ???

25. Thank You