FPGA Field-programmable gate array

Transcription

1 FPGA Field-programmable gate array What is FPGA? History of FPGA ASICs and ASSPs Vs. FPGA. FPGA Application. List and comparison of FPGA companies FPGA Architecture. Altera FPGA Series Prepared By- Mohammed Abdul Kader Lecturer, EEE, IIUC

2 What is an FPGA? The field-programmable gate array (FPGA) is a semiconductor device that can be programmed after manufacturing. Instead of being restricted to any predetermined hardware function, an FPGA allows you to program product features and functions, adapt to new standards, and reconfigure hardware for specific applications even after the product has been installed in the field hence the name "field-programmable". You can use an FPGA to implement any logical function that an application-specific integrated circuit (ASIC) could perform, but the ability to update the functionality after shipping offers advantages for many applications. An FPGA contains programmable logic components called logic elements (LEs) and a hierarchy of reconfigurable interconnects that allow the LEs to be physically connected. You can configure LEs to perform complex combinational functions, or merely simple logic gates like AND and XOR. In most FPGAs, the logic blocks also include memory elements, which may be simple flipflops or more complete blocks of memory. 2

3 History of FPGA Field Programmable Gate Arrays popularly known as FPGAs is an alternative for implementation of digital logic in systems. They are prefabricated silicon chips that can be programmed electrically to implement any digital design. The first static memory-based FPGA (commonly called as SRAM based FPGA) was proposed by Wahlstrom in This architecture allowed for both logic and interconnection configuration using a stream of configuration bits. Later on the first commercial modern-era FPGA was introduced by Xilinx in It contained the low classic array of Configurable Logic Blocks (CLBs) and inputs/outputs. From that of first FPGA which contain 64 CLBs and 58 inputs and outputs, FPGAs have grown enormously in complexity. Today s modern FPGA now can contain approximately 330,000 logic blocks and around 1100 inputs and outputs. The basic architecture of FPGA consists of three major components: programmable logic blocks which implements the logic functions, programmable routing (interconnects) to implement these functions and I/O blocks to make off-chip connections. 3

4 ASICs and ASSPs An application-specific integrated circuit (ASIC) is an integrated circuit composed of electrical components, such as transistors, capacitors, and resistors, usually fabricated on a wafer composed of silicon or other semiconductor material that is customized for a particular use. Two examples of ASICs are a voice recorder or a high-efficiency Bitcoin miner. Application-specific standard products (ASSPs), on the other hand, are ICs that are dedicated to a specific application market and sold to more than one user (and hence, standard) in contrast to ASICs, which are designed and sold to a single customer. Some examples of ASSPs are microcontrollers and the system chips at the hearts of many smartphones and tablets. ASICs and ASSPs are specifically designed for dedicated functionality. Because of the tight control of their configuration, ASICs and ASSPs are very compact, inexpensive, fast, and low-power, which are all highly desirable traits in electronics design. Because their function is hard-wired at the time of manufacture, it isn t easy to change the functionality of a small part of the circuit. In fact, because these circuits are permanently fabricated on silicon wafers, you simply can t take apart the circuitry and replace it with something else. If you need to change something in the design, you have to scrap the whole chip and start from scratch. 4

5 Advantages of FPGA over ASICs and ASSPs Compared to ASICs or ASSPs, FPGAs offer many design advantages, including: Rapid prototyping Shorter time to market The ability to re-program in the field for debugging Lower NRE costs Long product life cycle to mitigate obsolescence risk 5

6 FPGA Applications Due to their programmable nature, FPGAs are an ideal fit for many different markets such as: Aerospace & Defense - Radiation-tolerant FPGAs along with intellectual property for image processing, waveform generation, and partial reconfiguration for SDRs. ASIC Prototyping - ASIC prototyping with FPGAs enables fast and accurate SoC system modeling and verification of embedded software Audio - FPGAs and targeted design platforms enable higher degrees of flexibility, faster time-to-market, and lower overall non-recurring engineering costs (NRE) for a wide range of audio, communications, and multimedia applications. Automotive - Automotive silicon and IP solutions for gateway and driver assistance systems, comfort, convenience, and in-vehicle infotainment. Broadcast - Adapt to changing requirements faster and lengthen product life cycles with Broadcast Targeted Design Platforms and solutions for high-end professional broadcast systems. Consumer Electronics - Cost-effective solutions enabling next generation, fullfeatured consumer applications, such as converged handsets, digital flat panel displays, information appliances, home networking, and residential set top boxes. 6

7 FPGA Applications (Cont.) Data Center - Designed for high-bandwidth, low-latency servers, networking, and storage applications to bring higher value into cloud deployments. High Performance Computing and Data Storage - Solutions for Network Attached Storage (NAS), Storage Area Network (SAN), servers, and storage appliances. Industrial - FPGAs and targeted design platforms for Industrial, Scientific and Medical (ISM) enable higher degrees of flexibility, faster time-to-market, and lower overall non-recurring engineering costs (NRE) for a wide range of applications such as industrial imaging and surveillance, industrial automation, and medical imaging equipment. Medical - For diagnostic, monitoring, and therapy applications, FPGA families can be used to meet a range of processing, display, and I/O interface requirements. Security - FPGA offers solutions that meet the evolving needs of security applications, from access control to surveillance and safety systems. Video & Image Processing - FPGAs and targeted design platforms enable higher degrees of flexibility, faster time-to-market, and lower overall non-recurring engineering costs (NRE) for a wide range of video and imaging applications. Wired Communications - End-to-end solutions for the Reprogrammable Networking Linecard Packet Processing, Framer/MAC, serial backplanes, and more Wireless Communications - RF, base band, connectivity, transport and networking solutions for wireless equipment, addressing standards such as WCDMA, HSDPA, WiMAX and others. 7

8 List and comparison of FPGA companies /manufacturers Xilinx Altera Lattice Semiconductor Microsemi (was Actel) QuickLogic 8

9 FPGA Architecture Each FPGA vendor has its own FPGA architecture, but in general terms they are all a variation of that shown in Fig. The architecture consists of Configurable logic blocks, Configurable I/O blocks, and Programmable interconnect. Also, there will be clock circuitry for driving the clock signals to each logic block. Additional logic resources such as ALUs, memory, and decoders may also be available. 9

10 FPGA Architecture (Cont.) Configurable Logic Blocks (CLBs): These blocks contain the logic for the FPGA. In the large-grain architecture used by all FPGA vendors today, these CLBs contain enough logic to create a small state machine as illustrated in Fig. The block contains RAM for creating arbitrary combinatorial logic functions, also known as lookup tables (LUTs). It also contains flip-flops for clocked storage elements, along with multiplexers in order to route the logic within the block and to and from external resources. The multiplexers also allow polarity selection and reset and clear input selection. 10

11 FPGA Architecture (Cont.) Configurable I/O Blocks: A Configurable input/output (I/O) Block, as shown in Fig, is used to bring signals onto the chip and send them back off again. It consists of an input buffer and an output buffer with three-state and open collector output controls. Typically there are pull up resistors on the outputs and sometimes pull down resistors that can be used to terminate signals and buses without requiring discrete resistors external to the chip. The polarity of the output can usually be programmed for active high or active low output, and often the slew rate of the output can be programmed for fast or slow rise and fall times. There are typically flip-flops on outputs so that clocked signals can be output directly to the pins without encountering significant delay, more easily meeting the setup time requirement for external devices. Similarly, flip-flops on the inputs reduce delay on a signal before reaching a flip-flop, thus reducing the hold time requirement of the FPGA. 11

12 FPGA Architecture (Cont.) Programmable Interconnect: In Fig, a hierarchy of interconnect resources can be seen. There are long lines that can be used to connect critical CLBs that are physically far from each other on the chip without inducing much delay. Theses long lines can also be used as buses within the chip. There are also short lines that are used to connect individual CLBs that are located physically close to each other. Transistors are used to turn on or off connections between different lines. There are also several programmable switch matrices in the FPGA to connect these long and short lines together in specific, flexible combinations. Three-state buffers are used to connect many CLBs to a long line, creating a bus. Special long lines, called global clock lines, are specially designed for low impedance and thus fast propagation times. These are connected to the clock buffers and to each clocked element in each CLB. This is how the clocks are distributed throughout the FPGA, ensuring minimal skew between clock signals arriving at different flipflops within the chip. 12

13 FPGA Architecture (Cont.) Clock Circuitry: Special I/O blocks with special high drive clock buffers, known as clock drivers, are distributed around the chip. These buffers connect to clock input pads and drive the clock signals onto the global clock lines. These clock lines are designed for low skew times and fast propagation times. FPGA Architecture Its easy to see that FPGAs can be summed up as islands of configurable "Logic Blocks" in a sea of programmable interconnect. The beauty of FPGAs is that both the Logic Blocks & the Interconnect are programmable. 13

14 Altera FPGA Series Altera offers customers a broad spectrum of FPGAs geared towards diverse markets and applications. Cyclone FPGAs Cyclone series FPGAs are the industry's lowest cost, lowest power FPGAs, ideal for high-volume, cost-sensitive applications. Use a Cyclone series FPGA alone, as a digital signal processor, or as a cost-effective embedded processing solution. Cyclone series FPGAs offer a wide range of density, memory, embedded multiplier, and packaging options. Newer families include integrated transceiver options (at data rates up to 5G). Arria FPGAs Arria series FPGA provide an optimal balance of performance, power, and price for mid-range transceiver-based applications. You'll find a rich feature set of functions (memory, logic, and DSP) combined with superior signal integrity in the devices. Arria series FPGAs feature on-chip transceivers that allow you to integrate more functions and maximize system bandwidth (at data rates up to 10G). Stratix FPGAs Stratix series FPGAs are the industry's highest bandwidth, highest density FPGAs, ideal for high-end applications. Newer families come with integrated transceiver options (at data rates up to 28G). Stratix series FPGAs simplify the challenges of signal integrity by providing transceivers with best-inclass jitter characteristics. Features such as Programmable Power Technology keep total power in check. 14