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## Acronyms & Glossary

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ABC  Absorbing Boundary Conditions. To calculate solutions to partial differential equations (PDEs) it is necessary to introduce artificial boundaries to limit the area of computation. ABCs are employed to truncate infinite domains in order to perform computations.

AC  Alternating Current. Although labelled current, AC refers to mains voltage, AC occurs when charge carriers in a conductor or semiconductor periodically reverse their direction of movement. The flow of electricity reverses periodically starting from zero, growing to a maximum, decreasing to zero, reversing and reaching the maximum in the opposite direction before again returning to zero. This cycle is repeated indefinitely and the number of cycles per second is called frequency.

A/D converter  Analogue-to-digital converter. A/D converters are electronic circuits for the digitization of analog signals included in every digital desk or cellphone. They transform analog information into a form suitable for digital handling via  amongst others  processing by a computer or by logic circuits, including arithmetical operations, comparison, sorting, ordering and code conversion. The conversion involves quantizing and encoding. Quantizing means partitioning the analog signal range into a number of discrete quanta and determining to which quantum the input signal belongs. Encoding means assigning a unique digital code to each quantum and determining the code that corresponds to the input signal.

Analog. The term derived from the modulation of the carrier wave being analogous to the fluctuations of the human voice or other sounds. In telecommunications, an analog signal is one in which a base carrier's alternating current frequency is modified (to add information to the signal), e.g. by amplifying signal strength or variation of frequency.

BERT  Bit Error Rate Test. BERT stands for the ratio of bit errors transmitted. In BERT a known pattern of bits is transmitted and the errors received are counted to figure the BERT.

CAD  Computer Aided Design. CAD systems originally merely automated drafting, now CAD has become an important technology used e.g. by engineers to build prototypes or to simulate entire operations. CAD software may also be highly specialized for creating products such as integrated circuits (see IC).

Chip. Synonyms: "silicon chip," "microchip" and "integrated circuit" (IC). The term derives from looking like a minute small thin piece of aluminium (maximum 1/16 inch square by 1/30 inch thick). Technically, it is a set of microminiaturized, electronic circuits fabricated on a single piece of semiconducting material. Digital chips used as processors, memory and for other information processing functions in computers. Chemically, a semiconducting material (silicon in the vast majority of chips) is combined with other materials to alter its electrical properties. The result is a (silicon) crystal ingot up to 12 inches in diameter that is either positively (p-type) or negatively charged (n-type).

Circuit. A complete path through which an electronic current can flow. An electrical device that provides a path for electric current to flow. The term is loosely used for any device or subsystem using electrical or electronic components.

CMOS  Complementary Metal Oxide Semiconductor (pronounced "c-moss"/"sea moss"). CMOS is a semiconductor technology for chips, microprocessors and other digital logic circuits characterized by short circuit times and sparse power consumption, and the most widely used integrated circuit design. CMOS is based on complementary metal-oxide semiconductors having a metal gate electrode placed on top of an oxide insulator, which in turn is on top of a semiconductor material thus allowing a high density of logic functions on a chip. For the next-generation wireless terminals with SHF and EHF band communication facilities the specific, sensitive RF modules will need to be combined with large, mostly digital circuitry in the same package and preferably even on the same die.

DAC  Digital-to-analogue conversion. Via DAC digital signals (which have a binary state) are converted to analog signals (which theoretically have an infinite number of states). A DAC is an electronic device for converting a digital code into an analog voltage or current cycle by generating the output voltage from the binary code. It might be contained on a single chip or even be one circuit within a chip.

DAE  differential algebraic equation. A DAE is a mathematical statement containing one or more terms representing the rates of change of continuously varying quantities. Differential equations are very common in science and engineering, as well as in many other fields of quantitative study, because what can be directly observed and measured for systems undergoing changes are their rates of change. The solution of a differential equation is, in general, an equation expressing the functional dependence of one variable upon one or more others; it ordinarily contains constant terms that are not present in the original differential equation. In ICESTARS, the DAEs describe the behavior of an electrical circuit that contains semiconductor devices whereas the partial differential equations constitute drift-diffusion equations modelling the semiconductor devices in the circuit.

dB  Decibel. The unit for measuring the relative intensities of sounds or the relative amounts of acoustic or electric power. Because it requires about a tenfold increase in power for a sound to register twice as loud to the human ear, a logarithmic scale is useful for comparing sound intensity. Thus, the threshold of human hearing (absolute silence) is assigned the value of 0 dB and each increase of 10 dB corresponds to a tenfold increase in intensity and a doubling in loudness.

DC  Direct current. DC is a flow of electric charge in one direction only, an electrical current that is used within the computer's electronic circuits.

Digital. Digital describes electronic technology that generates, stores, and processes data in terms of two states: positive and non-positive. Positive is represented by the number 1 and non-positive by 0. Thus, data transmitted or stored with digital technology is expressed as a string of 0's and 1's. Each of these state digits is referred to as a bit (and a string of bits that a computer can address individually as a group is a byte). Data are electromagnetically stored in the form of discrete digits. A digital system uses discrete (discontinous) values, usually but not always symbolized numerically (hence called "digital") to represent information for input, processing, transmission, storage, etc. By contrast, non-digital (or analog) systems use a continuous range of values to represent information.

ECB  Equivalent Complex Baseband.

EDA  Electronic Design Automation. EDA is a constructive technique for the design of integrated circuits. The complexity of todays chip production requires computer-assisted design for positioning, geometry and wiring of electronic components. EDA is a key feature to realize digital radio frequency design by using the computer to design, layout and simulate the performance of electronic circuits on a chip, thus being indispensable for the manufacturing process.

EHF  extremely high frequency.

EPSS  eElectronic Performance Support System. EPSS comprises applications running simultaneously with or embedded within other applications providing support for the user accomplishing specific tasks.

EM  electromagnetic. Loosely defined: the interaction between electric and magnetic fields. Electric charge in motion pertains or exhibits magnetism.

Electromagnetic spectrum. The entire frequency range of electromagnetic waves covers a wide range of wavelengths:

• radio frequency: an electromagnetic wave frequency between audio and infrared
• extremely low frequency (ELF): below 3 kilohertz
• very low frequency (VLF): 3 to 30 kilohertz
• low frequency (LF): 30 to 300 kilohertz
• medium frequency (MF): 300 to 3000 kilohertz
• high frequency (HF): 3 to 30 megahertz
• very high frequency (VHF): 30 to 300 megahertz
• ultrahigh frequency (UHF): 300 to 3000 megahertz
• superhigh frequency (SHF): 3 to 30 gigahertz
• extremely high frequency (EHF): 30 to 300 gigahertz

Electromagnetic (EM) Analysis and Simulation. EM simulation is needed to model high-frequency and high-speed circuits and devices and absolutely necessary to accurately verify the interactions between devices in the RF front-end at very high frequencies. Regarding the mere scale of EHF band communication front-ends it is impossible to run full simulations at the level of detail an EM analysis offers. Therefore EM analysis only looks at a small part of the total design, while the rest of the circuit is simulated at a higher level of abstraction.

FDTD  Finite-difference time-domain. Since about 1990, FDTD techniques have emerged as primary means to computationally model many scientific and engineering problems dealing with electromagnetic wave interactions with material structures. FDTD is a mathematical method to directly integrate time-dependant differential equations. FDTD being a time-domain method, solutions can cover a wide frequency range with a single simulation run. To be able to simulate a model on the level of an EM-field solver together with the transistor level models normally used in SPICE-like simulators, the finite-difference time-domain (FDTD) scheme often used in time-domain field solvers will in ICESTARS be replaced by an implicit scheme better suited for circuit simulation.

FEM  Finite Element Methods. FEM, a numerical method to solve differential equations, especially of elliptical partial differential equations, is a type of computer simulation using mathematical equations. With FEM a mathematical surface description of an object can be created, resulting in a model ready for analysis.

FT  Fourier Transformation. The name goes back to the French mathematician Baron Jean Baptiste Joseph Fourier (17681830). FT is a numerical method that transforms time signals into a frequency range. In informatics FT is usually implemented as Fast Fourier Transformation (FTT), efficient algorithms for computing involving a wide range of mathematics from complex number arithmetic to group and number theory.

GHz  GigaHertZ = one billion cycles per second. High-speed computers have internal clocks rated in GHz, and radio frequency applications transmit in this range.

GPS  Global Positioning System. Originally developed for U.S. military use as a satellite-based navigation and location system. The basis of GPS are more than 24 communications satellites transmitting signals globally 24 hours. A single GPS receiver can find its own position in seconds from GPS satellite signals to an accuracy of one metre.

HB  Harmonic Balance / Harmonic Balance Algorithm. The classical method for simulating RF circuits is the Harmonic Balance method (HB) that has become a standard technique in circuit simulation since the mid-1980s. HB is an analysis method that simulates a circuit under single- or multi-tone excitations. Nonlinear noise analysis is based on HB analysis and takes into account mixing phenomena from one frequency to another. HB, in principle, is a non-linear, steady-state simulation. Voltage and current sources create discrete frequencies resulting in a spectrum of discrete frequencies at every node in the circuit. Linear circuit components are solely modeled in frequency domain. Non-linear components are modeled in time domain and Fourier-transformed before each solving step.

IC  Integrated circuits. The term refers to the integration of several electronic components into one circuit. ICs are miniaturized and complex electronic circuits (consisting of, amongst others, semiconductor devices and passive components such as e.g. resistors and capacitors) that have been etched onto tiny chips of semiconductor material. ICs play a very important part in electronics. Most are specially made for a specific task and contain up to thousands of transistors, diodes and resistors.

IEEE 802.11 (also: Wireless LAN (WLAN), WiFi). Communication norm in wireless nets, published by the Institute of Electrical and Electronics Engineers (IEEE).

IMD  Intermodulation distortion. If two or different frequencies are simultaneously passed through an amplifier or mixed differently, new frequencies are created from the sum and difference of the original frequencies (= IMD). IMD has become increasingly important in microwave and RF amplifier design. As modulation techniques become more sophisticated, greater performance is required from amplifier and receiver circuits. IMD is measured as a percentage of the original frequencies with a lower specification being desired. E.g.: If a 100Hz and 150Hz tone are passed through an amplifier, the sum of the original frequencies (150 + 100 = 250Hz) and the difference (150 - 100 = 50Hz) will be generated. The intermodulation is caused by the non-linear behavior of the signal processing  and the theoretical outcome can be calculated via Volterra series (see Volterra).

Interference. Usually refers to the addition of unwanted signals to "useful" signals. It is anything, which alters, modifies or disrupts a signal as it travels along a channel between a source and a receiver.

LAN  Local Area Network.

LNA  Low Noise Amplifier. An amplifier that boosts the signal received from an antenna. It is located close to the antenna so that the signal can be amplified before additional noise is injected from the line and electronic circuits. (Source: Wikipedia.org).

LO  Local Oscillator

LTI  Linear, time-invariant system. In electrical engineering, specifically in circuits, signal processing, and control theory, LTI system theory investigates the response of a linear, time-invariant system to an arbitrary input signal. Though the standard independent variable is time, it could just as easily be space (as in image processing and field theory) or some other coordinate. Thus an alternately used term is linear translation-invariant. The term linear shift-invariant is the corresponding concept for a discrete-time (sampled) system. (Source: Wikipedia.org).

Moores law. Moore's law forecasts that the power of microprocessors will double every two years. By squeezing more and more components on to a silicon chip computers, e.g., are becoming ever more powerful. With in each test a million transistors being deposited onto a scintilla of silicon, Moores law is said to reach its physical limits within 20 years.

MOR  Model Order Reduction. MOR is a common task within the simulation, control, and optimization of complex physical processes. With MOR it is possible to study properties of dynamical systems in application for reducing their complexity, while preserving (to the possible extent) their input-output behaviour. MOR is also employed in numerical mathematics to solve equations (such as e.g. FEM) faster by finding an approximation of lower order.

MPDAE  Multi-rate partial differential-algebraic equations. In radio frequency (RF) applications, electric circuits produce signals exhibiting fast oscillations, whereas the amplitude and frequency may change slowly in time. Thus, solving a system of differential algebraic equations (DAEs), which describes the circuit's transient behaviour, becomes inefficient, since the fast rate restricts the step sizes in time. A multivariate model is able to decouple the widely separated time scales of RF signals and provides an alternative approach. Consequently, a system of DAEs changes into a system of multirate partial differential algebraic equations (MPDAEs). The determination of multivariate solutions allows for the exact reconstruction of corresponding time-dependent signals.

PAN  Personal area network. Transmitting data over a short distance of typically no more than two or three feet. Bluetooth is an example of a wireless PAN.

PDE  partial differential equation. Whereas DAEs are formulated with independent variables (usually time), PDEs feature two and more independent variables with unknown function(s). PDEs govern a lot of physical processes as there many variables depend on multiple other variables. One of the key tasks of numerical mathematics is to develop algorithms to efficiently solve them. The techniques of studying partial differential operators and the properties of these operators change depending on the "type" of operator. To calculate solutions to PDEs it is necessary to introduce artificial boundaries to limit the area of computation (see Absorbing Boundary Conditions - ABCs).

PLL  Phase-Locked Loop. A PLL generates a signal that has a fixed relation to the phase of n electronic circuit that compares an input frequency and phase to a reference signal. It then generates a voltage proportional to the difference between the input and the reference. PLLs are used in myriad digital and mixed mode (analog and digital) applications as regulators, demodulators, synchronizers and frequency multipliers and dividers.

Pseudocode. Pseudocode is a way to represent an algorithm, aiming to achieve a balance between the understandability and informality of a natural language (e.g. English) and the precision of programming code. A pseudocode should describe the entire logic of the algorithm so that an implementation into a specific software framework becomes a simple translation process of the lines of pseudocode into corresponding programming language syntax.

ePSS  (Electronic) Performance Support System. A computer system that provides quick assistance and information without requiring prior training to use it. It may incorporate all forms of multimedia delivery as well as AI techniques such as expert systems and natural language recognition.

ODE - ordinary differential equation. In mathematics, an ODE is a relation that contains functions of only one independent variable, and one or more of its derivatives with respect to that variable. (Source: Wikipedia.org). In ICESTARS, ODEs play an important part in the mathematical modelling of (technical) problems.

Oscillator. An electronic circuit used to generate high-frequency pulses. In electronic oscillators, electrons oscillate with a constant period and also require the addition of energy to replace energy loss. Electronic oscillators are used to generate alternating current and high-frequency currents for carrier waves in radio broadcasting. They are incorporated in a wide variety of electronic equipment.

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RF  Radio Frequency. The range of electromagnetic frequencies above the audio range and below infrared light (from 10 kHz to 300 GHz). Except for infrared (IR) transmission all wireless transmission uses RF, including AM and FM radio, TV, satellites, portable phones, cellphones and wireless networks. RF signals can be focused in one direction (directional), or they can transmit in all directions (omnidirectional). The range of frequencies and power output determine how well RF signals can penetrate walls and other objects. Signals up to 2 GHz can generally go through dense objects, but from 2 GHz to 5 GHz, they have some difficulty. From 5 GHz to 50 GHz, signals require line of sight, but can traverse long distances. Signals above 50 GHz require line of sight, but only for short distances.

RFID  Radio Frequency Identification. A method for uniquely identifying an object using a tag or module that carries a unique ID number or code. Identification can be made using wireless (RF, or radio-wave) connection, meaning no line-of-sight or physical contact is needed. There are many different ways to achieve RFID. The tag, also known as an electronic label", "transponder" or "code plate", is made up of an RFID chip attached to an antenna. Transmitting in the kilohertz, megahertz and gigahertz ranges, tags may be battery-powered or derive their power from the RF waves coming from the reader.

SHF  Superhigh frequency.

Signal. A signal renders information defined by an amplitude value or transformation of a physical value in time or another physical dimension. Signals, whose parameter constitute an information only of value and time functions is called analogue signal. If the signal on the contrary is constituted only of characters with every character representing a certain value of the signal parameters, it is called digital signal.

SiP  System in a Package. SiPs perform most of the functions of an electronic system. Contrary to System-on-a chip (see SoC) SiP consists of a number of integrated circuits enclosed in a single package. The term refers to semiconductor circuits that enclose in a single package or module a number of integrated circuits. All functions, usually executed by a single chip, are amalgamated in the SiP. The advantage of SiP technology is its flexibility as active and passive devices and digital and analog circuits can be combined, thus building a complete functional unit in a multi-chip package.

SME  Small and medium enterprises.

SoC  System-On-Chip. As the name tells, System-on-a-Chip is a complete electronic system built on a single chip. The more functions contained within the chip, the more systems can be miniaturized for handheld use with an ancillary reduction in power. A SoC for a telecom application might e.g. contain a microprocessor, digital signal processor (DSP), RAM and ROM and even a graphics processor.

Spectrum. An ordered array of the components of an emission or wave.

SPICE  Simulation Program with Integrated Circuit Emphasis. SPICE, originally developed in 1975 at University of California, Berkeley, USA, is a powerful circuit simulator that is widely used in industry to verify circuit designs and to predict the circuit behaviour.

Transformation. Every transformation aims at transforming data to a different representation yielding an advantage for further operations and procedures.

VCO  Voltage Controlled Oscillator. An oscillator device, in which output frequency is proportional to its input voltage. A VCO can be tuned over a wide range of frequencies by applying a voltage (tuning voltage) to it.

Volterra Analysis. Modern integrated radio systems require highly linear analog/RF circuits. Two-tone simulations are commonly used to study a circuits nonlinear behaviour. Very often, however, this approach suffers limited insight. To gain insight into nonlinear behaviour, we use a multisine analysis methodology to locate the main nonlinear components (e.g. transistors) both for weakly and strongly nonlinear behaviour. Under weakly nonlinear conditions, selective Volterra analysis is used to further determine the most important nonlinearities of the main nonlinear components.

VoHB  Volterra-on-Harmonic Balance Analysis. The VoHB technique was VoHB was developed in J. Aikio's doctoral thesis as a technique to be able to see a detailed construction, dominant causes and cancellation mechanisms of nonlinear distortion in analog circuits. Further development of the method is continued in ICESTARS (Integrated Circuit/EM Simulation and Design Technologies for Advanced Radio Systems-on-chip), where nine partners are developing circuit simulation and analysis techniques for future mm-band radio circuits.

Wafer. The approximately 1/30th of an inch thick slices of the ingot (see chip) are called wafers. The manufacturing of semiconductors begins with a wafer, in the following processes transistors and other structures are defined and interconnected by conductors. Then the wafer is sliced into "dice", which are mounted in packages, creating the IC (see integrated circuit). then in various processes transistors.

Wavelet. The term derives from the French ondelette ("small wave"), it was transferred to English by translating "onde" into "wave", giving "wavelet". Wavelets are purposefully crafted to have specific properties that make them useful for signal processing. As a mathematical tool wavelets are used to extract information from many different kinds of data by dividing a given function or continuous-time signal into different scale components. Each scale component can then be studied with a resolution that matches its scale.

# The ICESTARS Glossary

As ICESTARS comprises different areas of Radio Frequency design a lot of abbreviations are used. Our glossary lists the acronyms of difficult or specialized terms with their accompanying definitions employing an alphabetized, dictionary-style format