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USL1V330MDD_Datasheet PDF

来源:LM317 Electronics Components编辑:ASSMANN WSW Components时间:2021-06-15 15:45:35

The output power in the supply voltage control example shown in Figure 1 is related to the quadratic of the supply voltage. The fact that there is a simple quadratic relation between control signal and RF output power provides four advantages:

So how do programmers utilize DSP features that the C language was never designed to handle, yet still achieve portability and highly efficient compact code? The answer is to use one of a number of variants of the C language, coupled with the use of advanced simulation tools and compilers. The relative efficiency of these C-language variants depends on how easily they allow programmers to reach the unique features of DSPs at the C-language level.

The C language was originally developed in the early 1970s for programming general-purpose computers such as the DEC PDP-11. Because of the diversity of the applications that were run on these computers, they utilized floating-point arithmetic and had large contiguous memory spaces—an architecture that is still used today in the ubiquitous PC.

USL1V330MDD_Datasheet PDF

DSPs, however, have evolved for a very special purpose—namely to process real-world analog signals in the digital domain, often with the additional requirement of having to do so in real time. In many cases, this means that their hardware architecture is specifically designed to speed the execution of one type of instruction—the multiply-accumulate instructions needed to execute the Fourier series that lie at the heart of functions such as Finite Impulse Response (FIR) filters. To maximize the execution speed of this very specialized hardware architecture, DSPs therefore operate with fixed-point arithmetic and, simultaneously, fetch multiple operands from divided memory spaces.

Until very recently, DSPs were not programmed in high-level languages. They were programmed almost exclusively in assembler. Some were even hardwired to perform a single DSP function. With only a few hundred bytes of code required to implement the core of many DSP algorithms, the 'hand-crafting' required for these techniques was a practical proposition.

Today, however, two factors are forcing DSP programmers to use high-level languages. First, many of today's more flexible DSPs are quite capable of performing irregular DSP algorithms, such as speech codecs, as well as the highly regular 'tight-loop' algorithms required for functions such as FIR filters. You can also use these DSPs to implement system-control functions. This results in the need to write much larger programs, which is easier and quicker using a high-level language. Second, the short time-to-market requirements of very fast moving markets where DSPs are used extensively, such as in mobile telephony, demand that software is both reusable and portable. The only way to achieve these two objectives is high-level language programming,

USL1V330MDD_Datasheet PDF

So why choose C as a programming language for DSPs? The answer is simple. It is easy to learn and intuitive to use, which means that it is already ubiquitous within the programming community. Undeniably, the standard C programming language doesn't support the fixed-point arithmetic, divided memory spaces, and circular buffers that are typical of DSP architectures, but this article illustrates these are not insurmountable problems.

Only a few short years ago, if you asked when we would see efficient C-compilers for DSPs, even the experts would say that they were at least a decade away. Today, if you don't have a C-compiler for your latest DSP chip, then you don't stand a chance in the marketplace. The changing environment in which programmers now have to work means that they demand a C compiler.

USL1V330MDD_Datasheet PDF

One obvious way of coping with the problem is to program your DSP in C++, which allows you to define DSP-oriented classes such as a fixed-point data type, circular pointer, and circular array. Once you define these classes, you can use them to create corresponding objects that are manipulated using the language's standard operators (+, – , *, /, =, = =, !=, ,…) in a class-specific way. As a result, common operations on these DSP-oriented objects are given the same natural and intuitive feel as operations on C++ standard object types.

Because the definitions of new classes, and the way operators operate on them, are themselves written in C++, this approach has the advantage that your entire DSP program remains firmly within the language. Using C++ with DSP classes therefore goes a long way to meeting the requirements of maintainability and reusability. Programs written in this way can also be simulated and tested using standard software development tools and compiled using standard compilers.

Parsippany, N.J. — The UFX-EbNo series of carrier-to-noise (C/N) generators has been released for wireless LAN (WLAN) and cable modem testing applications. These instruments support five operating modes: C/N. Eb No , carrier-to-noise density (C/No ), carrier-to-interference (C/I), and noise generator. The instruments operate over variable power levels (-55 to + 5 dBm) and at frequencies up to 44 GHz. They are also equipped with an optional automatic gain control (AGC) that corrects input signal drift up to 0.2 dB resolution.

Availability: Now Data Sheet: http://noisecom.com/content/Products/Components/UFX_EbNo/ufxEbNo.html

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NEW YORK — Designers should be aware of several gotcha's” that can impede designs moving from ASICs to FPGAs, said Mike Dini of The Dini Group in a presentation Wednesday (Nov. 6) at the SoC Online conference, sponsored by EE Times.

Dini detailed the obstacles to such a conversion, compared today's main FPGA architectures and gave his take on the tools available for FPGA designs.

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