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System on chip (SOC)
Saturday, 06 January 2007
System on a chip (SOC) is an integrated circuit that includes a processor, a bus, and other elements on a single monolithic substrate. A system on a chip may include a configurable logic unit. The configurable logic unit includes a processor, interface, and a programmable logic on the same substrate. Integrated circuits are used in a wide variety of electronic equipment, including portable or handheld, devices. Such handheld devices include personal digital assistants (PDA), CD players, MP3 players, DVD players, AM/FM radio, a pager, cellular phones, computer memory extension (commonly referred to as a thumb drive or USB flash disk), etc. Such electronic technologies have facilitated increased productivity and reduced costs in a number of activities, including the analysis and communication of data, ideas and trends in most areas of business, science, education, and entertainment. Such portable devices are commonly manufactured using application specific integrated circuit (ASIC) designs. Advances in integrated circuit technology have led to the birth and proliferation of a wide variety of integrated circuits, including but not limited to application specific integrated circuits, microcontrollers, digital signal processors, general purpose microprocessors, and network processors. ASIC (application specific integrated circuit) technology has evolved from a chip-set philosophy to an embedded core based system-on-a-chip (SoC) concept. Design of ASICs often involves the design of various building block circuits that make up the ASIC. Significant resources are usually expended performing the design tasks associated with designing connection between building block circuits and adding the necessary support logic to complete a system on a chip (SoC), such as adding input/output (I/O) cells, clock distribution and test logic. Advances in integrated circuit technology have made it possible to embed an entire system, including a processor core, a memory unit, a high performance bus, and a programmable logic, in a single semiconductor device. This type of programmable semiconductor device is commonly referred to as a system-on-chip (SoC), or a configurable system-on-chip (CSoC). SOC differs from simple circuit integration in that many different types of circuits can be included on a single chip. For example, an SOC could include a computer processor, various signal processors, a large amount of memory, various clocks, power down circuits, and necessary system controllers all integrated on a single piece of silicon or integrated into a single package. In general, system-on-chip (SoC) technology is the ability to place multiple function "subsystems" on a single semiconductor chip. The various types of subsystems that may be integrated within the semiconductor chip include microprocessor and micro-controller cores, digital signal processors (DSPs), memory blocks, communications cores, sound and video cores, radio frequency (RF) cells, power management, and high-speed interfaces, among others. The term "system-on-chip" may be used to describe many of today's complex ASICs, where many functions previously achieved by combining multiple chips on a board are now provided by one single chip.

In recent years, there have been great advancements in the speed, power, and complexity of integrated circuits, such as application specific integrated circuit (ASIC) chips, random access memory (RAM) chips, and microprocessor chips. These advancements have made possible the development of system-on-a-chip (SOC) devices. SoCs are built using pre-designed models of complex functions known as "cores" (also known as intellectual property or IP) that serve a variety of applications. An SoC IC includes various reusable functional blocks, such as microprocessors, interfaces, memory arrays, and DSPs (digital signal processors). Such pre-designed functional blocks are commonly called "cores". A SOC integrates a plurality of cores into a single silicon device, thereby providing a wide range of functions in a highly compact form. A system-on-a-chip may contain combinations of cores of different functions such as microprocessors, large memory arrays, audio and video controllers, modem, internet tuner, 2D and 3D graphics controllers, DSP functions, and etc. An SOC comprises its own processor core (often referred to as an "embedded" processor), and will further comprise one or more cores for performing a range of functions often analogous to those of devices in larger-scale systems. System-on-a-chip (SOC) data processors are characterized by a very high degree of integration on a single integrated circuit (IC) chip. Many of the peripheral components now integrated onto the same IC chip as a processor core would have been implemented as separate IC chips in a previous generation of processors. An embedded processor or controller can be a microprocessor or microcontroller circuitry that has been integrated into an electronic device as opposed to being built as a standalone module or plugin card. Advancement of field-programmable gate array (FPGA) technology has led to the development of FPGA-based system-on-chip (SoC), including FPGA-based embedded processor SoCs. An FPGA comprises any number of logic modules, an interconnect-routing architecture and programmable elements that may be programmed to selectively interconnect the logic modules to one another and to define the functions of the logic modules. An FPGA circuit can be programmed to implement virtually any set of digital functions. Input signals are processed by the programmed circuit to produce the desired set of outputs. Such inputs flow from the user's system, through input buffers and through the circuit, and finally back out the user's system via output buffers referred to as input/output ports (I/Os). System-on-chip (SOC) devices typically include internal memory for storage of information such as instructions and/or data. Internal memory blocks in an SOC device typically occupy substantial chip area of an integrated circuit (IC) chip that contains the SOC device. Memory blocks of SOC devices and memory chips used as information storage devices traditionally include read only memory (ROM) blocks, which are typically used only for reading, and random access memory (RAM) blocks, which may be written as well as read. RAM blocks typically include static random access memory (SRAM) blocks and dynamic random access memory (DRAM) blocks. An SOC containing a DRAM and an analog device generally includes a capacitor used as a unit cell for a DRAM.

A system-on-chip is an IC designed by stitching together multiple stand-alone VLSI designs (cores) to provide full functionality for an application. The Advanced Microcontroller Bus Architecture (AMBA) standard is an open industry bus architecture that may be used for system on chip (SoC) designs. The bus architecture may incorporate a variety of system components that may include, e.g., a micro-controller, memory interface and blocks of peripheral interface logic. A system on chip (SOC) product provides many advantages and benefits over a traditional, separate component integrated circuit (IC) product. Integrating all system components into one chip or a plurality of chips in a single module affords a smaller product size, higher speed, and increased reliability. The separate IC product generally includes components that are connected to each other on a printed circuit board. Alternatively, an SOC product is designed such that an entire system (processors, memory, logic, clock, I/O control unit, etc.) can be implemented or embedded on a single chip, thereby producing a product that is smaller, faster, and more efficient than the separate IC product. SOC products provide faster chip speeds due to the integration of the components/functions into one chip. Many applications such as high-speed communication devices (VoIP, MoIP, wireless) require chip speeds that may be unattainable with separate IC products. Integrating chip components/functions into one chip eliminates the need to physically move data from one chip to another, thereby producing faster chip speeds. A SoC device allows nearly all of the components of a complex system, such as a cell phone or a television receiver, to be integrated onto a single piece of silicon. This level of integration greatly reduces the size and power consumption of the system, while generally also reducing manufacturing costs. The reduction in size afforded by SOCs also leads to improvements in power consumption and device speed. Circuit operations that occur on a single integrated circuit require much less power than a similar circuit implemented on a PCB with discrete components. While a microprocessor chip requires ancillary hardware electronic components to process instructions, a system on chip can include all required ancillary electronics. For example, a SoC for a cellular telephone can include a microprocessor, encoder, decoder, digital signal processor, RAM and ROM. FPGA-based SoCs with embedded operating systems (OSs) have further enhanced their popularity and flexibility.