Showing papers on "Radio frequency published in 1995"

Radio frequency circuit and memory in thin flexible package

Abstract: The present invention is a novel thin and flexible radio frequency (RF) tag that comprises a semiconductor circuit that has logic, memory, and radio frequency circuits, connected to an antenna with all interconnections placed on a single plane of wiring without crossovers. The elements of the package (substrate, antenna, and laminated covers) are flexible. The elements of the package are all thin. The tag is thin and flexible, enabling a unique range of applications including: RF ID tagging of credit cards, passports, admission tickets, and postage stamps.

Radio-Frequency Capacitive Discharges

Abstract: Basic Principals of the RF Capacitive Discharge Excitation of an RF Discharge Electron Motion in an Oscillating Electric Field Electrodynamic Plasma Characteristics and Interaction with Oscillating Field Electron Production and Loss: Plasma Maintenance A Simplified Model of the RF Discharge Constant Positive Plasma Potential Stochastic Heating of Electrons RF Discharge Modes Moderate-Pressure RF Discharge Space Charge Sheaths Experimental Current-Voltage Characteristics CVC and Normal Current Densities in the a-Discharge (Theory and Numerical Simulation) The a-g Transition Parameters The y-Discharge The a-g Transition at Moderate and Low Pressures Coexistence of Two RF Modes in the Gap High-Pressure RF Capacitive Discharges RF Discharge with Coated Electrodes Low-Pressure RF Discharges and Asymmetry Effects Self-Bias in an Asymmetric Capacitively Coupled Discharge Correlations Between Plasma and Sheath Parameters in an Ambipolar Diffusion-Controlled Discharge Sheath Dynamics and Current Anharmonicity in an Asymmetric Discharge Current Anharmonicity in Asymmetric and Symmetric Discharges Battery Effect in an Asymmetric Discharge Plasma 'Nontransparency' and Fast Electron Response to RF Field and 'Oscillationless' Sheath Ions The Floating Potential The a-Sheath The Energy Spectrum of Ions Bombarding the Electrode Surface RF Discharge in Electronegative Gases Smooth a-g Transition and the g Mode Some Aspects of Stochastic Heating of Electrons Numerical Simulation of Low-Pressure RF Discharges Magnetron RF Discharge Experimental Methods and Measurements Voltage Measurements and Current-Voltage Characteristics Probe Measurement of Constant Space and Plasma Potentials Active DC Probing of an RF Discharge A Method for Studying the Transverse Discharge Structure Optical Methods for the Study of Spatial Discharge Structure Laser-Induced Fluorescence and Laser-Optogalvanic Spectroscopy Excitation and Control of an RF Discharge Application of RF Capacitive Discharges for Gas Laser Excitation and Plasma Technology RF Discharge and Gas Lasers: A Brief History Arguments in Favor of RF Laser Excitation Frequency Dependence of Discharge and Active Laser Medium Parameters Selection of Designs and Parameters of Transverse RF-Excited CO2 Lasers with Diffusional Cooling Optical Resonators of Waveguide and Slab RF CO2 Lasers High Flowrate CO2 Lasers Excited by RF and Combined RF-DC Discharges Lasers with Alternative Active Media Magnetic Stabilization of Slab Discharges Plasmachemical Technology References Index

A Surface Micromachined Miniature Switch For Telecommunications Applications With Signal Frequencies From DC Up To 4 Ghz

Abstract: A surface micromachined miniature switch has been made on a semi-insulating GaAs substrate using a suspended silicon dioxide micro-beam as the cantilevered arm, a platinum-to-gold electrical contact, and electrostatic actuation as the switching mechanism. This switch functions from DC to RF frequency, and has an electrical isolation of -50 dB and an insertion loss of 0.1 dB at 4 GHz. The low process temperature budget of 250°C ensures the switch’s monolithic integration capability with microwave and millimeter wave integrated circuits.

Wireless vehicle parameter monitoring system

Abstract: A wireless system for monitoring vehicle parameters, such as tire pressure, using radio frequency (RF) signals transmitted from transmitters close in proximity to an associated parameter sensor, to a centrally located receiver. The transmitted RF signals from the transmitters may be distinguished by the frequency of the respective transmitted RF signals. To detect the presence of an RF signal having a particular frequency, the wireless vehicle parameter monitoring system of one embodiment includes a digitally controlled tuner or a plurality of parallel bandpass filters, which pass different ranges of frequencies corresponding to the frequencies of the RF signals output from the transmitters. In this manner, RF signals transmitted from different tires may be distinguished based upon the frequency of the transmitted signal. The receiver of this system may be implemented in the receiver of a trainable transmitter such that a dedicated receiver need not be provided.

Foundations and Industrial Applications of Microwave and Radio Frequency Fields: Physical and Chemical Processes

Abstract: ELECTRICAL ASPECTS. Governing Electromagnetic and Thermal Field Relations. Radio Frequency and Microwave Transmission. Microwave and Radio Frequency Circuit Design. High Power Applicators and Loads. Instrumentation and Measurement Methods. MATERIAL ASPECTS. Introduction to the Macroscopic Theory of Dielectrics. Dynamic Aspects. Generalization of Dielectric Relaxation in Real Materials. PROCESSING ASPECTS. Theoretical Models and Experimental Methods in High Power Density Electromagnetic Fields. Electromagnetic Processing of Homogeneous Materials at High Power Density. Electromagnetic Processing of Heterogeneous Materials at High Power Density. Microwave-Enhanced Catalysis. Index.

Low-power radio-frequency ICs for portable communications

Abstract: The contributions of integrated circuits to the RF front-end of wireless receivers and transmitters operating in broadcast and personal communications bands are surveyed. It is seen from this that when ICs enable a rethinking of the RF architecture, the wireless device can sometimes become significantly smaller, and consume much less power. Examples are taken from FM broadcast receivers, pagers, and cellular telephone handsets. Many semiconductor technologies are competing today to supply RF-ICs to cellular telephones. The various design styles and levels of integration are compared, with the conclusion that single-chip silicon transceivers, combined with architectures which substantially reduce off-chip passive components, will likely dominate digital cellular telephones in the near future. The survey also projects future trends for ICs for miniature spread-spectrum transceivers offering robust operation in the crowded spectrum. With sophistication in baseband digital signal processing, its increasing interaction with the RF sections, and with increasing experience in simplified radio architectures, all-CMOS radios appear promising in the 900 MHz to 2 GHz bands. A specific CMOS spread-spectrum transceiver project underway at the author's institution is discussed by way of example. >

Low-power monolithic RF peak detector analysis

Abstract: Closed-form expressions are derived for the transfer characteristic of a low-power monolithic RF peak detector. These are compared with computer simulation and experimental measurements. >

Low-power radio-frequency IC's for portable communications

Abstract: The contributions of integrated circuits to the RF front-end of wireless receivers and transmitters operating in broadcast and personnal communications bands are surveyed. It is seen from this that when 1C's enable a rethinking of the RF architecture, the wireless device can sometimes become significantly smaller, and consume much less power. Examples are taken from FM broadcast receiver, pagers, and cellular telephone handsets. Many semiconductor technologies are competing today to supply RF-1C's to cellular telephones. The various design styles and levels of integration are compared, with the conclusion that single-chip silicon transceivers, combined with architectures which substantially reduce off-chip passive components, will likely dominate digital cellular telephones in the near future. The survey also projects future trends for 1C's for miniature spread-spectrum transceivers offering robust operation in the crowded spectrum. With sophistication in baseband digital signal processing, its increasing interaction with the RF sections, and with increasing experience in simolified radio architectures, all-CMOS radios appear promising in the 900 MH z to 2 GH z bands. A specific CMOS spread-spectrum transceiver project underway at the author's institution is discussed by way of example

A 2.7 V to 4.5 V single-chip GSM transceiver RF integrated circuit

Abstract: This paper describes the design and implementation of a single-chip GSM (Global System for Mobile communications) transceiver RF integrated circuit. The chip includes the RF-to-baseband and baseband-to-RF (receive and transmit) functions, two fixed frequency PLL's, and a programmable frequency agile UHF synthesizer. It is implemented In a 1.5 /spl mu/m silicon bipolar process with 12 GHz NPN's and 110 MHz lateral PNP's. The receive path uses a single-IF solution including the RF mixer, quadrature demodulator, and variable gain IF amplifier on chip. The transmit path uses a direct-up architecture with an offset mixer and an output buffer capable of driving 0 dBm into 50 /spl Omega/. The frequency agile UHF synthesizer switches between receive and transmit modes and settles to within /spl plusmn/50 Hz (0.1 ppm) in less than 500 /spl mu/s. The UHF synthesizer includes all the synthesizer logic and the oscillator on chip. The only external components are the loop filter and tank circuit. This paper first explains the chip architecture decisions and block level descriptions. The transistor level circuit designs and layout are then discussed. Finally, the performance of the circuit performance versus the requirements is presented.

Direction finding and "smart antennas" using software radio architectures

Abstract: Operational tests and demonstrations of systems based on software radios are currently being performed in the 800 MHz mobile cellular radio band. These field trials are for mobile unit geolocation systems and adaptive phased array "smart antenna" applications. The geolocation system trials are in response to the demand for high confidence geolocation of mobile units for enhanced emergency 911 service and for use in the US Department of Transportation's Intelligent Vehicle Highway System (NHS) initiative. The smart antenna array application addresses the cellular service providers' need for more user channel capacity and/or geographic coverage from existing base station installations. Software radio architectures were selected because of their ability to provide superior performance at low life cycle cost. These systems use 4 to 8 wideband coherent channels and fully characterize the arriving RF energy to either geolocate the emitter or to maximize the carrier-to-interference ratio. >

Diode modulator for radio frequency transponder

Abstract: A diode modulator which is not part of the rectifier power supply circuit of an RF Transponder is controlled by the transponder electronic logic and memory circuitry to conduct RF current from a second terminal to a first terminal of the RF Transponder antenna in a first state of the transponder electronic circuitry, and does not conduct appreciable current in a second state of the transponder electronic circuitry, thereby changing the loading of the RF Transponder antenna between the first state and the second state of the transponder electronic circuitry, and thereby changing the intensity of the RF radiation backscattered from the RF Tag. The present invention has further advantages that the same diode used as a modulator can also be used in the transponder receiver circuit.

A tyre condition monitoring system

Abstract: A tyre condition monitoring system (1) comprises a wheel transmitter unit (2) for each wheel of a vehicle. The transmitter unit is mountable in the wheel and has sensors (9, 10) for sensing pressure and temperature in and rotation of the wheel. Signals from the sensors are processed by a processor (9) to produce data which is transmitted via a radio frequency transmitter (23). The data is transmitted with data representing a unit identity code. Transmitted data is received by a receiver unit (5, 6, 7) where it is analysed to determine the condition of the tyre. The receiver unit includes a user operable input for setting threshold limits for the temperature and/or pressure such that if a threshold is passed an alarm is sounded. Each wheel transmitter unit includes a power supply and is arranged so that power is only applied during the sensing and transmission of data. Intervals between transmissions of data can be varied depending on whether rotation of the wheel has been sensed.

Wireless radio modem with minimal interdevice RF interference

Abstract: A wireless radio modem for incorporation into a host system includes radio frequency modulation/demodulation circuitry employing electronic device elements that operate in a frequency range that minimize the RF interference between the radio modem and the host system. Radio modem power conservation is further maximized by 1) simplifying signal modulation processing by use of a single sideband suppressed carrier waveform transition table, thereby reducing processing requirements; and 2) incorporating a "sleep mode" feature in which all non-timer circuitry is powered-down when not in use.

Radio frequency volume coils for imaging and spectroscopy

Abstract: An electromagnetic shield for an NMR radio frequency coil designed to resonate at a selected Larmor frequency. The shield includes an electrically conductive layer surrounding the coil. This electrically conductive layer has a thickness substantially the same as one skin depth at the selected Larmor frequency. As such, the conductive layer efficiently conducts radio frequency currents at the selected Larmor frequency thereby conducting and containing the radio frequency coils at the selected Larmor frequency within the coil. Simultaneously, an electrically conductive layer, due to its thinness, very inefficiently conducts eddy currents of the type induced by the lower frequency DC gradient current switching transients the gradients are utilized to magnetically localize an image slice or volume. Consequently, the conductive layer simultaneously attenuates low frequency eddy current propagation of the type induced by the switching field gradient currents in the NMR application, and therefore does not substantially shield or effect the gradient fields across the coil.

Duplex RF repeater for personal communications system

Abstract: A duplex RF repeater for use in a personal communications system distributes and enhances time division duplexed signals at a single RF carrier. The duplex RF repeater includes an up-link amplifier and a down-link amplifier which amplify the time division duplexed signals at the single RF carrier. The repeater also includes a down-stream antenna, which links the repeater with a subscriber, and a controller which decreases the gain of one of the up-link or the down-link amplifiers when an RF signal is present at the other of the up-link or the down-link amplifiers to prevent self-oscillation caused by over coupling between the two amplifiers.

Method of selectively reducing spectral components in a wideband radio frequency signal

Abstract: A method of selectively reducing a magnitude of spectral components of a wideband analog radio frequency (RF) signal at an input to an analog-to-digital (A/D) converter is provided. The method includes the steps of digitizing the input to the A/D converter, analyzing the digitized inputs for relatively large spectral peaks, and notch filtering the relatively large peaks to a threshold value.

Method for deflecting the arc of an electrodeless hid lamp

Abstract: The present invention provides a method for using electrodeless high-intensity discharge (HID) lamps for automotive headlamp and similar applications requiring high/low beam operation (first and second beam orientation) of signaling. The HID lamp is excited with a high-frequency radio frequency (rf) signal. Modulation of the radio frequency signal is used to cause the arc of the HID lamp to selectively operate at an acoustic resonance point. At such a point, the arc undergoes a perturbation and is physically displaced from its quiescent position. When the lamp is placed at a focal or light-gathering point of an optical system having forward gain, displacement of the arc away from the focal point causes discernible changes in the far-field output of the optical system.

Location-ruled radio-integrated network

Abstract: An integrated radio frequency communication system, known as a Location-Ruled Radio-Integrated Network (LORRAINE) system, provides integrated voice, data and location services. The radio frequency communications system combines time division multiplexing (TDM) techniques with optional time division duplexing (TDD) or frequency division duplexing (FDD) techniques to provide a plurality of time slot channels for these services. Spread spectrum techniques help reduce noise and interference in the system.

Electrical characteristics of argon radio frequency glow discharges in an asymmetric cell

Abstract: Measurements of the current and voltage at both electrodes of a parallel-plate, capacitively coupled RF discharge cell (the Gaseous Electronics Conference Reference Cell) were combined with measurements of the voltage on a wire inserted into the glow region between the electrodes, for argon discharges at pressures of 13-133 Pa and peak-to-peak applied voltages /spl les/400 V Together, these measurements determined the RF voltage, current, impedance, and power of each sheath of the plasma Simple power laws were found to describe changes in sheath impedances observed as voltage and pressure were varied An equivalent circuit model for the electrical behavior of the discharge was obtained The equivalent circuit model can be used to relate the electrical data to plasma properties such as electron densities, ion currents, and sheath widths The results differ from models previously proposed for asymmetric RF discharges, and the implications of this disagreement are discussed

A microwave noncontact identification transponder using subharmonic interrogation

Abstract: This paper presents the design and analysis of a novel microwave radio (RF/ID) transponder that has been developed for remote identification of personnel and articles, such as in "wireless key" entry systems. Based on a subharmonically pumped quasi-optical mixer, the transponder is activated by a C-band interrogation beam to upconvert and radiate a digitally modulated identification tone at two X-band frequencies. These response signals are nonharmonically related to the interrogation signal. The frequency conversion process is analyzed using a Volterra series model that includes the effects of self-bias current, coupled with a scattering metric that is directly useful in radio link calculations. >

Plasma treatment apparatus and method

Abstract: A plasma treatment apparatus comprising a chamber earthed, a vacuum pump for exhausting the chamber, a suscepter on which a wafer is mounted, a shower electrode arranged in the chamber, opposing to the suscepter, a unit for supplying plasma generating gas to the wafer on the suscepter through the shower electrode, a first radio frequency power source for adding radio frequency voltage, which has a first frequency f 1 , to both of the suscepter and the shower electrode, a second radio frequency power source for adding radio frequency voltage, which has a second frequency f 2 higher than the first frequency f 1 , at least to one of the suscepter and the shower electrode, a transformer whose primary side is connected to the first radio frequency power source and whose secondary side to first and second electrodes, and a low pass filter arranged in a circuit on the secondary side of the transformer, and serving to allow radio frequency voltage, which has the first frequency f 1 , to pass through it but to cut off radio frequency voltage, which has the second frequency f 2 , while plasma is being generated.

High-Q inductors in standard silicon interconnect technology and its application to an integrated RF power amplifier

Abstract: This paper presents the highest Qs (up to 24) reported for inductors integrated by using standard silicon technology with multi-level interconnects, and the implementation of such an inductor in an integrated 675 MHz, 100 mW power amplifier.

Multiformat auto-handoff communications handset

Abstract: Disclosed is an apparatus and method for supporting communications and handoffs between multiple signal formats at multiple carrier frequencies. Antenna circuitry which includes a linearly polarized antenna and a circularly polarized antenna is utilized to receive and transmit the multiple signal formats at the multiple carrier frequencies simultaneously. A pair of RF signal paths each including RF transmit circuitry, RF receive circuitry and RF processing capabilities are utilized to support simultaneous communications between two signal formats. A multisystem controller in communications with each RF signal path initiates and completes handoffs between the multiple signal formats utilizing both RF signal paths to achieve uninterrupted communications across a large service coverage area.

MRI front end apparatus and method of operation

Abstract: A front end unit (32) for a magnetic resonance imaging (MRI) system (20) comprises a plurality of coil attachment ports (46) to which an RF signal or tuning signal is selectively routed thereby permitting, during operation, coils (22) to remain attached to each of the plurality of ports. A signal routing controller (28, 30) selects to which of the ports the RF signal or tuning signal is to be routed. The RF front end unit (32) is also known as the relay switch board assembly or RSB. Each port of the RF front end is attached to a different RF coil or RF coil combination. Tuning and imaging operations can be conducted for a plurality of coils in succession, without coils having to be detached from the RF front end. The signal routing controller selectively applies the RF signal (from an RF unit) or the tuning signal (from a tuning controller) to the selected coil through a signal path unique to the selected coil. Coils not selected to be operative can be detuned.

CMOS high-speed dual-modulus frequency divider for RF frequency synthesis

Abstract: The architecture of a high-speed low-power-consumption CMOS dual-modulus frequency divider is presented. Compared to other designs fabricated with comparable CMOS technologies, this architecture has a better potential for high-speed operation. The circuit consumes less power than previously reported CMOS circuits, and it approaches the performance previously achieved only by bipolar or GaAs devices. The proposed circuit uses level-triggered differential logic to create an input-frequency-entrained oscillator performing a dual-modulus frequency division. In addition to high-speed and low-power consumption, the divider has a low-input signal level requirement which facilitates its incorporation into RF applications. Fabricated with a 1.2-/spl mu/m 5-V CMOS technology, the divider operates up to 1.5 GHz, consuming 13.15 mW, and requiring less than 100 mV rms input amplitude. >

Generation of radio frequency modulated optical radiation

Abstract: The invention relates to the generation of radio frequency modulated optical radiation, in particular for use in a radio over fibre communications system. It has been found that a semiconductor electroabsorption modulator can efficiently modulate an input optical signal at harmonics of the electrical modulation frequency applied to the electroabsorption modulator. A low frequency design, and thus low cost, electroabsorption modulator can be utilised to generate higher order harmonics of an electrical drive signal for use in a radio over fibre communications system.

Apparatus for RF shielding radio circuitry

Abstract: First and second shielding portions (110, 112) formed of electroless plated plastic enclose a radio frequency (RF) board (108). Bosses (148) extend from inner surfaces (130, 142) of the first and second shielding portions (110, 112) to make contact with compressible ground clip members (126) located on the RF board (108).

Circuit module for a phased array radar

Abstract: A circuit module for a phased array radar (10) incorporates radar frequency (RF) mixers (54a, 54b) connected to an RF splitter/combiner (52) and to in-phase and quadrature RF reference signals. The RF mixers (54a, 54b) are also connected to intermediate frequency (IF) processing circuitry (60 to 68) providing for phase control of RF signals and IF reference signals. In transmission mode, the RF mixer (54a, 54b) receive phase-controlled, digitally synthesised IF signals from clock-activated generators (68a, 68b). Their outputs are combined at the RF splitter/combiner (52) to provide single sideband upconversion of the phase-controlled IF signals. In reception mode, the RF splitter/combiner (52) and the RF mixers (54a, 54b) act as an image rejection mixer circuit in which the phase-controlled IF signals are local oscillator signals. Beamforming is carried out by computer control of the IF phase together with, in the case of reception, analogue or digital summation of output signals from an array of modules (12).

A 1 GHz CMOS RF Front-End IC with Wide Dynamic Range

Abstract: A 1 GHz Low Noise Amplifier and Mixer combination has been integrated in a standard 1?m CMOS process. The circuit is matched to 50? at the input, and drives a 50? load. Overall conversion gain is 22 dB, noise figure is 3.5 dB, and the IIP3 of the combination is +12 dBm. The fully balanced circuit drains 8 mA from 3V.