Digital signal processors (DSPs) are becoming prevalent in the electronics industry. Digital signal processors are developed to manipulate analog signals in digital form, and find applications in image processing, telecommunications, audio processing, multimedia presentations and other areas for processing the signals in real time. The explosive growth in telecommunication and multimedia applications demands flexible, efficient, high performance digital signal processing (DSP) devices. In audio applications, the DSP is used for digital signal processing which requires the real time nature, such as filtering, reverberation addition processing, and so on for audio signals. A digital signal processor is used for a reverberator, equalizer and mixer and also for constructing digital filters such as an infinite impulse response filter (IIR) and finite impulse filter (FIR). A digital signal processor is used also as a tone source, envelope generator, a reverberation effect device etc. of an electronic musical instrument. The digital signal processors have found increasing application in portable apparatus, such as cell phones, wireless internet devices, etc. Digital signal processors are used in mobile phones, cordless phones, wireless personal digital assistant (PDA) devices, cable modems, local area network (LAN) cards, and a host of radio frequency (RF) communication devices, including conventional and high-definition television (HDTV) sets and radio receivers. DSPs are used in a broad range of embedded consumer and industrial communications products (e.g. cellular phones, modems, call processing systems, wireless base stations, video conferencing systems, routers, etc.). In digital cellular communications systems, DSPs are often employed to process digital audio signals resulting from the sampling of analog speech. The demand for DSP computation capability in this field is driven by the increasing needs of applications such as GPS position location, voice recognition, low-bit rate speech and audio coding, image and video processing, and 3G cellular modem processing. These digital cellular systems require the analog speech signals to be digitally coded in a manner that reduces the required bandwidth of the analog speech signal and minimizes the susceptibility of the digitally encoded speech to noise. A digital signal processor is used also in various other fields including precision control, a high quality television and a video tape recorder. New and expanded applications for DSPs are continuously being created.

Depending on the calculating operations to be undertaken, various types of digital signal processors are available for the respective application. The digital signal processor chip generally includes a memory device, arithmetic logic device, multiplier, register, controller, and a bus for transmitting data between the respective components. The bus includes local buses and a global bus configured so that the global bus is used for transmitting data between local buses and the local buses are used for transmitting data between associated components and the global bus. A digital signal processor is typically characterized by a multiple bus structure with separate memory spaces for data and program instructions and arithmetic units designed to perform multiply-accumulate operations very rapidly. Digital signal processors typically include a data bus, an instruction bus, a program control unit, data memory, program memory, and an arithmetic unit. The data bus provides a means for transferring data between the data memory, external memory, the arithmetic unit, and the control unit. The instruction bus provides a means for the program control unit to retrieve instructions from the program memory and provides such instructions to the arithmetic unit. A digital signal processor includes at least one memory for storing digital signal processing operations instructions as well as operands used in the digital signal processing operations, and a core processor, connected to the memory, for carrying out such operations. A digital signal processor may include additional random access memory (RAM), read-only memory (ROM), input/output device drivers or bus interface control circuits. A digital signal processor also includes a peripheral input/output (I/O) device enabling communication with, and the transfer of data to/from, other processors and/or external devices. The core processor includes a control block, an instruction alignment buffer connected to a primary instruction decoder, and at least one computation block for performing the digital signal processing operations. The core processor may use several different computational schemes and data storage and transfer schemes for optimizing speed, accuracy, size and performance. The computation unit includes a register file, a multiplier/accumulator, an arithmetic logic unit (ALU), and a shifter. The register file receives operands from memory and supplies the operands to the computation units for use in the digital signal computations. Digital signal processors usually include a multiply and accumulate (MAC) unit which multiply two or more operands together and add the product to a value already stored in an accumulator. A typical general purpose digital signal processor (DSP) includes a controller which decodes instructions, by controlling operations of a high speed data path, registers, and a memory address generator. In order to be integrated into a large data processing system, digital signal processors use a variety of additional peripheral circuits.

Digital signal processing involves the digital representation of signals and the use of digital processors o analyze, modify, or extract information from such signals. Processing by a digital signal processor is pipeline-controlled, and it is divided into three steps, including fetching of an instruction, decoding of the instruction and execution of the instruction for instance. A variety of types of operations are needed for a digital signal processor to accomplish desired tasks. These operations are performed on data elements, operands, and the like and typically include mathematical operations, logic operations, shifting operations, and other data manipulation operations. These operations may be identified in program instructions and may be executed by functional units, execution units, processing elements, or the like. Digital signal processors can do array or block oriented calculations. The arrays or blocks of data typically correspond to a multiword, digitized sample of an analog signal. The ability of digital signal processors to perform high-speed arithmetic, input/output (I/O) and interrupt processing operations has made them popular in communications applications. Digital signal processor applications are typically characterized by real time operation, high interrupt rates and intensive numeric computations. A digital signal processor has an ability to perform a higher accurate processing compared to an analog signal processor. The DSP is capable of evenly obtaining arbitrary characteristics by setting parameters such as coefficients and achieving non-adjustment. Digital signal processor is also capable of processing an analog signal by means of a digitizing method. A digital signal processor (DSP) performs computations which generally require large numbers of arithmetic operations to be performed rapidly. Digital signal processing can be performed more rapidly than analog signal processing using techniques such as high-precision and stability processing, pipeline control, and parallel processing. For this reason, this DSP has been used in a wide field such as a voice signal processing, a communication signal processing, a measurement signal processing, an image signal processing, an earthquake wave signal processing and a underwater acoustic signal processing. Digital signal processors are commonly used to perform real-time computationally intensive data processing applications.

Digital signal processors are designed to process digital signals in real time using built in computational units. A digital signal processed by a DSP is a signal capable of conveying a discrete number of magnitudes. A digital signal is typically a series of numbers, or digital values, used to represent a corresponding analog signal. A digital signal may be created from an analog signal through sampling and quantizing the analog signal. A digital audio signal may be transformed by digital reverbation into an output signal representing the sound and its reflections in the specified acoustical environment. A DSP transforms a received digital signal to an output digital signal. The transformation may involve filtering out undesired portions of the received digital signal. Filtering is used to remove certain frequencies from a received signal while leaving other frequencies intact. A digital signal processor may also perform signal transformations such as digital delay, digital reverbation, and signal enhancement. A digital signal processor may perform more complex function which reshapes the received digital signal into an output digital signal which is substantially different from the received digital signal. Such transformations may be mathematically represented as fast Fourier transforms (FFTs), discrete Fourier transforms (DFTs), or Z transforms. Finite impulse response (FIR) filters implement a filtering algorithm comprised of multiplying the input or delayed elements of the input with coefficients and summing the products to obtain an output. In order to achieve the computational speed required of the digital signal, digital signal processor designs may be optimized with respect to different operating parameters, such as computation speed and power consumption, depending on intended applications. The computing power of DSPs can be enhanced by using reduced instruction set (RISC) computing techniques which include using smaller numbers of like sized instructions to control the operation of the DSP. The use of RISC computing techniques increases the rate at which instructions are performed. This increases the overall computing power of the DSP.