Showing papers on "Balun published in 1988"

Broadband and baseband LAN

Abstract: Described is a communications system for transmitting baseband and broadband signals simultaneously. The system is ideally suited for interconnecting different types of data terminal equipment (DTE) within a building or limited geographical area. The system includes a backbone communications network formed from a plurality of independent communications systems. Each of the plurality of independent communications systems is dedicated to transmit either the baseband signals or the broadband signals. A Filter Coupler (FC) network combines and separates the two different type of signals at the distribution level. One embodiment of the FC includes a filter network coupled in tandem with a high frequency transformer. In an alternate embodiment the FC includes a balun transformer coupled to a directional coupler transformer.

Monolithic double balanced mixer with high third order intercept point employing an active distributed balun

Abstract: A monolithic double balanced mixer with a high third order intercept point employs a local oscillator signal which is applied to the input port of a first active distributed element balun. The balun has two outputs which are applied via amplifiers to respective inputs of a double balanced resistive FET quad mixer. The double balanced resistive FET quad mixer employs four MESFETs arranged in a ring configuration. Two additional inputs to the quad mixer are obtained from a second balun which is also of an active distributed element configuration and receives at the input the RF signal. The quad mixer operates to produce mixing of the LO and RF signals at the outputs thereof. The outputs of the quad mixer are applied to a combiner which operates to combine the outputs of the quad mixer to produce at the combiner output an IF signal. The combiner can be a common gate combiner configuration with active loads or a distributed configuration employing FET devices in a distributed transmission line type of circuit.

Double balanced mixers using active and passive techniques

Abstract: A variety of microwave double-balanced mixers, using dual-gate FETs or diodes as the mixing nonlinearities, have been fabricated in planar monolithic circuit technology The mixer topologies, which use active balancing methods, eliminate the need for large suspended substrate structures, thus minimizing circuit area and facilitating integration These approaches also eliminate IF extraction problems and allow the best performance characteristics of FETs and diodes to be combined The mixers are insensitive to DC bias and RF termination variations and require only one balun, which can be active or passive They exhibit excellent decade-band performance with overlapping frequency response on all ports >

Balun circuit for radio frequency coils in magnetic resonance systems

Abstract: A balun circuit arrangement for radio frequency (RF) coils in magnetic resonance (MR) systems. The balun circuit arrangement comprises a conductor having a length equal to a quarter wavelength at the tuned resonance frequency of the (RF) coil.

Method for providing multiple coaxial cable connections to a radio-frequency antenna without baluns

Abstract: A method for providing plural coaxial cable connections, each to a different portion of a single radio-frequency (RF) antenna without requiring the use of isolation means at any RF connection, determines at least a point within the antenna having a desired common potential adjacent to each of the different portions to which one of the coaxial cable connections is to be made; Then forms a separate segment of each different portion which is located substantially at the common potential and is reactively separated from adjacent segments of the associated portion; and connects a shield conductor of an associated coaxial cable to the separate segment, while connecting a center conductor of that same associated coaxial cable to a selected one of the adjacent segments of that different portion

Low temperature plasma generator with minimal RF emissions

Abstract: A low temperature plasma generator having reduced radio frequency (RF) emissions, and a method for reducing the RF emissions of a plasma generator. A low temperature plasma generator (100) includes a pair of electrodes (150 and 160) that are energized by an RF power supply (138) through a balanced impedance matching network (200). The impedance matching network includes a balun transformer (158), matched variable inductors (222 and 230), a fixed capacitor (240) in parallel with a variable capacitor (244) and a fixed capacitor (242) in parallel with a variable capacitor (246). The RF potential on electrodes (150 and 160) varies sinusoidally between opposite positive and negative values with respect to ground potential, such that the net potential on the two electrodes with respect to ground is always substantially equaol to zero, thus eliminating a glow discharge current and radiation emissions that otherwise are produced by similar prior art low temperature plasma generators.

High level wide band RF mixer

Abstract: A wide band RF mixer includes a first bifilar balun transformer coupling a high level source of RF signal to the input winding of a trifilar balun transformer. The two output windings of the trifilar balun transformer are connected in series with the drain-source circuits of a pair of GaAs FET transistors. The source of each FET transistor is connected to ground. A local oscillator has a symmetric output signal that is coupled to a self-bias network and also to the gate electrodes of said FETs. An IF output signal is taken between ground and a common junction of the output balun windings. The arrangement provides a high level mixer with good intermodulation characteristics for ultra high frequencies.

Analysis of suspended microstrip taper baluns

Abstract: The baluns used in broadband microwave mixers are often in the form of suspended microstrip circuits with tapered conductors. These structures have been analysed using TEM theory of the even and odd modes and results are presented for typical cross-sections. Tapers were approximated by cascading short lengths of uniform line and calculations and measurements were carried out on various tapers. The performance of the baluns is poor at frequencies where the even mode resonates. Between the resonances, the tapers perform better as a balun than a similar structure using uniform strips of equal width. The resonances can be damped by suitably loading the even mode.

Low distortion and low noise oscillator-mixer IC for CATV converters

Abstract: A low-distortion and low-noise oscillator-mixer IC sufficient for practical use in CATV (cable television) converters has been successfully developed. The IC consists of a double-balanced mixer (DBM), a voltage-controlled oscillator (VCO), and balance-unbalance converters (baluns). To obtain high IM/sub 2/ (second-order intermodulation distortion) and low noise figure, special care for designing the IC was taken to suppress the unbalance in the DBM and baluns and to obtain high g/sub m/ in constituent FETs. The converter using the presented IC has superior characteristics to those of conventional converters by 15-20 dB in IM/sub 2/, 2-3 dB in noise figure, and less than -20 dB in local isolation for the CATV band. >

AC line filter with tapped balun winding

Abstract: An AC line filter having a balun coupled to an AC voltage input and an AC voltage output. The balun includes a first and a second set of windings with a first and a second tap on the first and second set of windings, respectively. A first Y capacitor is connected to a ground and the first tap of the first set of windings of the balun, and a second Y capacitor is connected to the ground and a second tap of the second set of windings of the balun.

Broadband monolithic single and double ring active/passive mixers

Abstract: Several double balanced multi-octave bandwidth mixers, comprised of active center-tapped baluns and diode rings are discussed that were fabricated using planar monolithic circuit technology. This novel balun topology uses common gate and common source circuit techniques, so that an ideal 180 degrees phase shift occurs for the signals present between the upper and lower halves of the circuit. The balun exhibits excellent balance through the design band on 2-18 GHz. The performance of a center-tapped balun, designed to operate throughout the 2 to 18 GHz frequency band, is described for both up-converter and down-converter mixer designs. >

High efficiency amplifier

Abstract: Amplifiers operating in push-pull are implemented to obviate input baluns and output signal combiners and their attendant losses. Amplifiers having two signal branches that each receive the input signal and have their signal branch outputs connected directly together. Each branch operates during alternate half cycles of the input signal while direct combining of the branch signal outputs produces a composite signal corresponding to the complete input signal. Each branch includes a matching input circuit and a heterojunction bipolar transistor whcih may be configured in either common collector or common emitter arrangement. The transistors are different since one is an NPN while the other is a PNP but they are selected to have similar direct current and radio frequency characteristics.

A distributed double-balanced dual-gate FET mixer

Abstract: A double-balanced dual-gate FET mixer, which is very insensitive to DC bias and RF termination variations, has been fabricated using monolithic circuit technology The unique approach requires only one balun (balance-unbalance converter), which can be either active or passive and exhibits excellent decade-band performance with overlapping frequency response on all ports It is concluded that this device can be used as a broadband upconverter as well as a conventional mixer in a variety of receiver applications In addition, since the mixer is completely balanced, the IF frequency response can overlay the LO (local oscillator) or RF responses which usually can only be accomplished with a double-double balanced structure >

A C-band low-noise MMIC phased array receive module

Abstract: The development of a low-cost, high-yield GaAs module containing five monolithic ICs-two gain stages, two active baluns and a two-bit phase shifter with on-chip active isolator-is discussed. Also included are logic decoders, level shift circuitry, and two microwave low-noise amplifiers. The receive module attains 50-dB gain and 2-dB noise figure across the 4-6-GHz band and is realized in a 2.2 in*1.1 in * 0.6 in housing. System architecture and receiver subsystem results are provided. >

Communication system for transmission of broadband and baseband information

Abstract: Communications system for transmitting baseband and broadband signals simultaneously, which is ideally suited for interconnecting different types of data terminal equipment (DTE) within a building or limited geographical area. The system includes a backbone communications network (10) formed from a plurality of independent communications systems, being each dedicated to transmit either the baseband signals or the broadband signals. A Filter Coupler network combining and separating the two different type of signals at the distribution level includes a filter network coupled in tandem with a high frequency transformer. In an alternate embodiment the coupler includes a balun transformer coupled to a directional transformer.

Broadband Phase Shifters using RC-Allpass-Networks and Active Balun Circuits

Abstract: Synthesis procedures for symmetrically and unsymmetrically loaded RC-allpass bridge circuits are presented. Phase shifters with 900 ± 200 from 1 MHz to 4 GHz are obtained by switching between two RC-allpass networks of second order and a section of line in one of the RC-allpasses. With active balun circuits the overall transmission loss is close to 0 dB.

Design of a very broadband dipole

Abstract: The techniques involved in designing a 2.5:1 bandwidth dipole above a finite ground plane are described. The antenna was computer-modeled using the method-of-moments technique. The balun network was designed to match the actual dipole impedance using microwave circuit computer-aided design techniques. Measured results verify the dipole operation over a bandwidth in excess of 2.5:1 with a gain better than 7 dBi and a SWR below 2. The dipole/balun is found to be simple to construct and is well suited for use as a single radiator or as a phased-array element. >

Simple impedance transforming feed system for low-gain quadrifilar and bifilar satellite terminal antennas

Abstract: An impedance transforming balun feeder system has been devised for low-gain antennas such as quadrifilar helices and spirals, consisting of four coaxial cables and a microstrip circuit. The arrangement allows physically orthogonal ‘balanced air’ outputs with quadrature phasing, in space limited configurations.

A Wide-Band Printed Circuit Dipole

Abstract: : A printed circuit dipole with integrated balun is presented that has achieved measured bandwidths of 40 percent over a 2:1 VSWR range. The microstrip balun features a double-tuning capability that provides the diploe with an impedance match over a wide band of frequencies. Simple transmission line theory is used to analyze the balun structure, whereas the method-of-moments is utilized to determine the dipole current distribution. Two dipoles were fabricated and tested in order to validate the dipole/balun design equations. Antenna patterns are taken at several frequencies over the operating band to determine any frequency dependence of the patterns. VSWR measurements and cross- polarization patterns are also presented.

Doublly balanced mixer

Abstract: PURPOSE:To realize an inexpensive doublly balanced mixer with small size and high performance at UHF-SHF bands by using two rat race circuits known conventionally and specifying the arrangement CONSTITUTION:In exciting a port 41, an output level having a delay of 90 deg at a port 42 and having a delay of 270 deg or the like is caused, but no output is produced at a port 43 Since the phase difference of the output between the ports 42 and 44 is 180 deg, a balun using a rat race circuit is realized by utilizing the port 41 as an unbalanced input and the ports 42, 44 as two balanced outputs Then a diode quad 6 is arranged at the inside of a ring line 4 being the rat race circuit to attain the miniaturization Moreover, the ring lines 4, 5 being two rat race circuits (baluns) are mounted at both sides of pattern faces 25, 26 of a ground conductor to attain the constitution of the connection without sacrifycing the symmetry of the circuit in the shortest distance and the doublly balanced mixer with excellent characteristic is realized

Microwave band variable attenuator

Abstract: PURPOSE:To miniaturize the titled attenuator without characteristic deterioration at a high frequency band by connecting a diode to a 1/4 wavelength three-wire coplaner balun via a strip line different from lambda/4 wavelength, applying a control voltage to each diode, attenuating a signal in response to a control voltage and synthesizing the result so as to obtain an output signal. CONSTITUTION:An input signal is subjected to unbalanced-balanced conversion by a coplaner balun 1, divided into two signals of equal amplitude and opposite phase, and they are respectively fed to pin diodes 2, 3 through strip lines 4a, 4b. In this case, since the strip line 4b is longer than the strip line 4a by lambda/2, the signals are fed to the pin diodes 2, 3 with equal amplitude and phase. Since a dias voltage is fed to the pin diodes 2, 3 via a bias line 5, the resistance of the pin diodes varies in proportional to the voltage, the input RF signal is attenuated, and outputs of the pin diodes 2, 3 are synthesized and the result is extracted as the output signal. Thus, no earth current flows, a wide band characteristic is provided and the titled attenuator is constituted in miniaturization.