Showing papers on "Balun published in 2002"

A derivation of a class of 3-port baluns from symmetrical 4-port networks

Abstract: This paper describes an approach in deriving the general conditions that need to be satisfied for a class of 3-port baluns. This is done by analyzing the behavior of a general symmetrical 4-port network when one of the ports is terminated with an arbitrary impedance. These conditions will be useful in devising new balun structures and in deriving exact design equations for such baluns. Examples will be presented for some known and new baluns in this class. These insights have also made the cascading of multisection baluns possible by specifying the overall requirements for the cascaded structures. Based on these results, a 3-section, Marchand-type, coupled-line balun has been designed and fabricated. Good agreements between simulation and measured results have been obtained, thereby verifying the validity of the design equations.

Lumped and distributed lattice-type LC-baluns

Abstract: This paper presents two balun circuits derived from the lumped Lattice-type LC-balun. First the lumped LC-balun bridge elements are substituted by microstrip lines. This results in an improved performance at the 2nd and 3rd harmonic frequency for RF power amplifier output baluns. Secondly, the lumped Lattice-type LC-balun is extended to a dual band balun. Independent impedance transformation and balun conversion can be done at two different frequencies. The design equations are derived.

Converting baluns into broad-band impedance-transforming 180/spl deg/ hybrids

Abstract: A technique for converting baluns into 180/spl deg/ hybrids by adding an in-phase power splitter is presented in this paper Incorporating the broad-band antiphase and in-phase power splitting characteristics of the balun and power splitter results in a 180/spl deg/ hybrid with broad-band characteristics This technique also provides a means of achieving perfect matching and output isolation for three-port lossless baluns Applying this technique to a Marchand balun will result in a broad-band impedance-transforming 180/spl deg/ hybrid Simple design equations based on the scattering matrix are presented These theoretical results are validated by an experimental 180/spl deg/ hybrid using a coupled line Marchand balun It achieves amplitude balance of 05 dB and phase balance of less than 5/spl deg/ from 12 to 32 GHz

Package filter and combiner network

Abstract: A transceiver front end circuit includes an antenna terminal capable of being coupled to an antenna. A first balun circuit has a single input that is coupled to the antenna terminal, and a pair of balanced outputs coupled to a corresponding pair of balanced receiver inputs. The first balun circuit matches an input impedance of the pair of balanced receiver inputs and substantially phase shifts the input reflection coefficient of the pair of balanced receiver inputs by about 180-degrees. A second balun circuit has a single output coupled to the antenna terminal and a pair of balanced inputs coupled to a corresponding pair of balanced transmitter outputs. The second balun circuit matches an output impedance of the pair of balanced transmitter outputs and substantially phase shifts the output reflection coefficient of the pair of balanced transmitter outputs by about 180-degrees. The first balun circuit and the second balun circuit can be contained within a single package. A first shunt switch can be coupled across the pair of receiver inputs. A second shunt switch can be coupled across the pair of transmitter outputs.

Integrated circuit low noise amplifier and applications thereof

Abstract: An integrated low noise amplifier includes an on-chip balun, a line impedance matching circuit and an on-chip differential amplifier. The on-chip balun is operably coupled to convert a single ended signal into a differential signal. The line impedance matching circuit is operably coupled to the primary of the on-chip balun to provide impedance matching for a line carrying the single ended signal. The on-chip differential amplifier is operably coupled to amplify the differential signal and is impedance matched to the secondary of the on-chip balun.

Triple balanced mixer

Abstract: A triple balanced mixer has a compact size and is readily assembled. The triple balanced mixer has a planar substrate that is formed from several layers of low temperature co-fired ceramic. The substrate has a top layer, a bottom layer and inner layers. Vias extend through the substrate. A local oscillator balun and RF balun are located on the inner layers. An intermediate frequency balun is mounted to the top layer. Diode rings are mounted on the top layer. The diode rings are electrically connected to the local oscillator balun, the RF balun and the intermediate frequency balun through the vias.

Full-wave analysis of choking characteristics of sleeve balun on coaxial cables

Abstract: An optimal design for a sleeve balun with maximum choking on a coaxial cable is determined using a full-wave body of revolution finite difference time domain method with perfectly matched layer boundary conditions. An analysis of the sensitivity of choke length L and outer diameter R/sub 2/ on choking effectiveness was carried out. A balun with L=77.5 mm (0.232/spl lambda//sub 0/) and R/sub 2/=8 mm on a cable with R/sub 1/=2 mm (R/sub 2//R/sub 1/=4) results in an S/sub 21/ of -20 dB at 900 MHz and -15.5 dB at 2730 MHz. The isolation of the balun at 900 MHz is quickly degraded as the R/sub 2//R/sub 1/ ratio is reduced below 2. Increasing R/sub 2//R/sub 1/ to 8, results in a reduction of optimum balun length L to approximately 0.215/spl lambda//sub 0/, approximately 14% shorter than the typical recommended length for an 'ideal' quarter-wave balun.

Balancing networks for symmetric antennas .I. Classification and fundamental operation

Abstract: Emphasis has been placed on the quality of a metrology antenna system that allows it to be represented accurately using analytical or numerical models. Central to this capability is the efficacy of the balancing networks, sometimes referred to as balanced to unbalanced transformers (baluns). In this paper, we classify three fundamental types of baluns and show that all three can be derived from the 180/spl deg/, four-port hybrid network. Balanced antennas driven from coaxial feed lines and operated in the presence of an asymmetric scatterer present an intrinsically unbalanced load to the balun. We show that in such situations the current balun is the only appropriate balun to employ. For numerous antenna metrology applications, in particular, site attenuation measurements, 180/spl deg/, four-port hybrid networks have been employed as baluns. Network relations are derived relating the so-called voltage and current baluns to the 180/spl deg/, four-port hybrid network. It is shown that, in addition to acting as a 0/spl deg/ or 180/spl deg/ power divider, the hybrid network can serve as either a voltage or a current balun depending on the termination at the isolated port. In contrast to the traditional approach, it is shown that when using a 180/spl deg/ hybrid as a balun, the isolated port should be terminated in such a way that the hybrid behaves as a current balun as opposed to a 180/spl deg/ power divider. This will yield experimental results that can be more readily reconciled with models.

Electromagnetic simulation of some common balun structures

Abstract: Baluns serve many applications in RF and microwave communications, radar, and instrumentation equipment. The word balun is an acronym for balanced-to-unbalanced converter, and the function is employed to change a single-ended signal, i.e., a signal that is referenced to ground, to a balanced signal with equal potentials with respect to ground but opposite polarity. These balun structures are employed in such common RF and. microwave components as mixers' antenna-feed networks, and frequency multipliers. In this paper some common balun structures are investigated using the electromagnetic simulation software package Microwave Office, available from Applied Wave Research. The Microwave Office design suite is an integrated software package that includes an object-oriented linear and nonlinear circuit simulator as well as a full-wave, electromagnetic analysis of planar, physical structures that may be imported within the circuit simulator.

Integrated broadside coupled transmission line element

Abstract: A novel broadside-coupled transmission line element is disclosed. The element includes a first metallization layer that has a first spiral-shaped transmission line and at least one bridge segment formed therein. The element also includes a second metallization layer that has a second spiral-shaped transmission line and connector segments formed therein. The connector segments provide respective electrical conduction paths between the inner area of the first and second transmission lines and the outer area of the first and second transmission lines. A first one of the connector segments is electrically connected to the inner terminus of the second transmission line. The second transmission line has a gap at each intersection with the connector segments. A dielectric layer lies between the first and second metallization layers. The dielectric layer has a plurality of apertures formed therein for providing electrical connections between the second transmission line and the bridge segment(s) of the first metallization layer, and for providing an electrical connection between the inner terminus of the first transmission line and a second one of the connector segments. The element is realized in an integrated circuit environment, and may be used to create various circuit elements such as baluns, balanced and unbalanced transformers and current and voltage inverters for operation at high frequencies.

Ultra-wideband planar coupled spiral balun

Abstract: A coupled transmission line balun construction employs two pairs of planar interleaved spiral coils ( 3, 5 & 7, 9 ) formed on an electrically insulating or semi-insulating substrate ( 11 ) defining a planar structure. One coil in each pair is connected in series to define the input transmission line of the balun, with one end ( 8 ) of that transmission line being open circuit. The balun provides an ultra-wide bandwidth characteristic in the frequencies of interest for MMIC devices, is fabricated using the same techniques employed with fabrication of MMIC devices, and is of a physical size that lends itself to application within MMIC devices.

Laminated balun transformer

Abstract: Line elements 24 and 27 are connected in series through a relay terminal 43, to constitute an unbalanced transmission line. Line elements 25 and 28 each constitute a balanced transmission lines. The strip lines 24 and 25 are electromagnetically coupled to constitute a coupler. Similarly, the line elements 27 and 28 are electromagnetically coupled to constitute a coupler. A ground terminal G1 is connected to the balanced transmission lines, which are constituted by the line elements 25 and 28. Meanwhile, A shield terminal G2 is connected to leading portions 30a to 32a of shield electrodes 30 to 32. These two terminals G1 and G2 are electrically independent of each other.

A semi-lumped balun fabricated by low temperature co-fired ceramic

Abstract: A new chip-type multi-layer ceramic balun is presented in this paper. This balun is designed in the ISM band and fabricated using low temperature co-fired ceramic (LTCC) technology. It involves the semi-lumped concept and the multi-layer structure to realize the LTCC-MLC balun. The symmetric structure provides the excellent characteristics of phase balance and amplitude balancing. Measured results of the LTCC-MLC balun match well with the computer simulation.

Design method of a dual band balun and divider

Abstract: This paper presents the design method and performance characteristics of a dual band balun. The design method for dual band balun is based on the lumped element equivalent circuit of quarter-wave transformer. By employing the proposed configuration and the derived formulas, dual band balun are designed, simulated, and manufactured. The proposed design method and equivalent circuit can make it easy to adapt to designing dual band balun and divider of ceramic multi-layer chip type. The dual band balun and divider are applied to wireless communication system.

A 2.4 GHz polarization-diversity planar printed dipole antenna for WLAN and wireless communication applications

Abstract: This article presents the design simulation, fabrication and measured performance of a 2.4 GHz polarization-diversity printed dipole antenna for wireless communication applications. Two orthogonal printed dipole antennas, each with a microstrip via-hole balun for vertical and horizontal polarization, an combined and fabricated on a PCB substrate. PIN diodes are used as switches to select the desired antenna polarization. The 3D finite-element-method (FEM) electromagnetic EM simulator, HFSS, is used in the design simulation of this planar antenna structure. Numerical and measured results of the antenna radiation characteristics, including input SWR, radiation pattern coverage and polarization-diversity, are presented and compared.

Two-stage variable-gain mixer employing shunt feedback

Abstract: A demodulator which includes an active balun circuit and at least one mixer driven by the active balun circuit. The active balun circuit includes a negative shunt feedback arrangement.

Dual-channel passband filtering system using acoustic resonators in lattice topology

Abstract: A dual-channel passband filtering system having a first, second and third balanced ports for connecting, respectively, to a first transceiver, an antenna and a second transceiver. A first lattice-type passband filter is connected between the first and the second port, and a second lattice-type passband filter is connected between the second and the third port. A phase shifter is used to match the first and second transceiver and the second port. A balun can be used for each port to convert the balanced port to a single-ended port. In each passband filter, two series resonators are use to provide two balanced ends, and two shunt resonators are connected to the series resonators in a crisscross fashion to form a differential or balanced topology. The first and second passband filters have different frequencies.

Analysis and design of a high-performance planar Marchand balun

Abstract: This paper presents an enhanced Marchand balun that offers excellent amplitude and phase balance performance. The enhanced Marchand balun is designed using compensated coupled lines. It employs capacitive compensation, a renowned technique for compensating the unequal even- and odd-mode phase velocities encountered in parallel-coupled microstrips. Analysis carried out in this study has proven that the finite directivity of coupled lines significantly affects the balun performance. The proposed capacitively-compensated Marchand balun is demonstrated at 2.1 GHz and has offered excellent results.

Characteristic impedance of unbalanced TDR probes

Abstract: Time domain reflectometry (TDR) may be used to make simultaneous measurements of both dielectric constant and conductivity by means of a probe inserted into the medium. The air-spaced characteristic impedance of the probe is required in order to estimate the conductivity from the final value of the TDR waveform. Unbalanced probes derived from a coaxial line by replacing the outer shield with regularly spaced wires are favored for many applications because they eliminate the need for a balun. Until now, it has been necessary either to measure the probe characteristic impedance or to calibrate it in solutions of known conductivity. This paper shows how to deduce an expression for the probe characteristic impedance by means of a conformal transformation. For thin wires, a simpler formula has been derived which is suitable for hand calculation. The accuracy of these analytic expressions has been assessed by a method of moments numerical solution which exhibits very rapid convergence as extra basis functions are added. The characteristic impedance formula obtained by conformal transformation and its thin wire approximation are found to be accurate to 0.1% and 1%.

Wideband conical spiral antenna

Abstract: A spiral antenna having a horizontal member that terminates wires for conducting and radiating signals provides increased efficiency over the HF transmission range in a smaller size construction. A load having a parallel RLC circuit is provided at about the center of the horizontal member. The wires are provided in an elliptical pattern with the spacing between wires provided arithmetically. The wires are further configured symmetrically around a vertical support member. A balun transformer is also provided for impedance matching with a feed line.

Design of an LTCC integrated tri-band direct conversion receiver front-end module

Abstract: This paper presents the results of a front-end receiver module integrating GSM/DCS/PCS band select functions and a direct conversion IC on a low temperature cofired ceramic (LTCC) substrate. The front-end-module (FEM) integrated a SP3T GaAs PHEMT switch for band selection, three SAW filters for pre-selection, and a direct conversion IC for down conversion of the RF signal. Integrated passives included a PCS balun, direct conversion IC matching elements and structures to improve the performance of differential SAW filters. The LTCC module contained 24 embedded passives and 15 surface mount components integrated on a 328 mil/spl times/586 mil, 19-layer multi-layer integrated circuit (MLIC). Receiver sensitivity was better than -114 dBm, the system noise figure was less than 9 dB, and the return loss characteristics measured at the antenna input port were better than 10 dB for all three bands. EM simulation was used to achieve first pass design success and the modeling approach yielded excellent agreement between measured and simulated results.

Integrated radio having on-chip transformer balun

Abstract: A transformer balun is obtained that is symmetrical in structure, provides high current, or high voltage, amplification and has high coupling coefficients while maintaining minimal overall size. The balun structure includes primary and secondary metal windings at separate layer interfaces. The primary and secondary metal windings are symmetrical and can have any number of turns, which is only limited by integrated circuit area and capacitance. Accordingly, the primary and secondary windings may be on as many layers as needed. Further, the primary and/or secondary may include a center tap ground, which enables the winding to be used as a differential port.

Broadband balun and impedance transformer for push-pull amplifiers

Abstract: A balun and transformer system (201) is provided in which a balun (112) is cascaded between two 4:1 impedance transformers (102, 110) to form a 16:1 broadband impedance transformation for push-pull amplifier applications (200). The balun (112) is configured in a Marchand configuration. The balun and transformers (201) are formed with coupled lines realized with a very thin layer of ceramic. Additional coupling between the gap in the balun (112) is achieved by an embedded capacitor (260) built in the balun's ceramic. DC bias supply (294, 296) to the power amplifier (106) is achieved by using the hot plate of decoupling capacitors (298, 299), which serve as a floating ground plane to the whole application (200).

Integrated quadrature splitter-combiner and balun

Abstract: An integrated quadrature splitter-combiner and balun comprising: a transmission line balun operably connected to a first port and a second port; a first capacitor operably connected across the transmission line balun; a second capacitor operably connected to the first port and said balun; and a third capacitor operably connected to the second port and the balun. The second capacitor, the third capacitor, and the transmission line balun combine to form an RF splitter-combiner to split a balanced RF signal received at the first port into a first and second unbalanced quadrature RF signal transmitted at the second port and combines the first and second unbalanced quadrature RF signals received at the second port into the balanced RF signal transmitted at the first port.

Front end module

Abstract: Such a front end module is arranged as a module using an antenna switch ( 6 ), a low pass filter ( 5 ), a surface acoustic wave filter ( 7 ) and a balun ( 8 ) integrated by a multilayer substrate ( 11 ) and components incorporated in or mounted on the multilayer substrate ( 11 )

Single-chip 20-GHz VCO and frequency divider in SiGe technology

Abstract: This paper presents the design, implementation and testing of a fully integrated 20 GHz voltage controlled oscillator, a frequency divider with a divide ratio of 16, as well as an output driver. All blocks are integrated on one IC with an area of 890 /spl times/ 890 /spl mu/m/sup 2/ and are fabricated in a production SiGe bipolar technology. The VCO is a varactor-tuned LC-type oscillator with a tuning range of 600 MHz. The differential signal of the output driver is converted to a single-ended signal by an external microstrip balun and delivers a maximum of 2 dBm of output power into a 50 /spl Omega/ load. The chip works with a single supply voltage of 3.6 V, the VCO draws 12 mA of supply current, divider and output driver consume 17 mA and 51 mA, respectively. The measured phase-noise of the VCO is -85 dBc/Hz at 1 MHz offset frequency.

High power wideband balun and power combiner/divider incorporating such a balun

Abstract: A balun transformer includes a coaxial transmission line terminating at one end with balanced terminals and terminating at another end with unbalanced terminals. At least two impedance segments are connected in series between the balanced terminals and the unbalanced terminals, each of the at least two impedance segments being formed by a magnetic core and at least one winding of the coaxial transmission line wound about the magnetic core.

New termination for ultrawide-band slot spirals

Abstract: Slot-spiral antennas utilizing very shallow reflecting cavities have previously been demonstrated by the authors for extremely broadband-conformal applications. We have previously demonstrated the importance of an integrated planar balun and feed for realizing the slot spiral's bandwidth potential. Of equal importance, is the development of a termination that is applicable to the slot radiator. In this paper, we demonstrate a new slot spiral arm termination which, in conjunction with the reflecting cavity and planar infinite balun, allows for very thin yet extremely broadband spirals. The included measurements show that a slot spiral with a diameter of 5.75" and a thickness of merely 0.5" delivers a typical gain of 5 dB/sub ic/ from 750 MHz to 4 GHz with good axial ratio performance. Additional loading (both inductive and dielectric) applied to the same spiral can extend its operational bandwidth down to 200 MHz for the same size aperture.

Multi-circuit signal transformer

Abstract: Multiple digital audio transformer circuits are included in a module for mounting in a chassis. These digital audio transformer circuits are comprised of a front mounted twisted pair digital audio cable connector and a rear mounted coaxial cable connector, with circuitry including baluns electrically linking the front and rear connectors to reduce the impedance of the signal and attenuate the amplitude of the signal voltage. In one embodiment, the module may also include removable attenuation pads accessible through the front face of the module to allow variation of the level of voltage attenuation. The preferred embodiment of the module bi-directional transforms 110 Ohm digital audio signals and 75 Ohm coaxial signals. If transformation of other levels of impedance are desired, modules may also allow for removal and replacement of the baluns. A digital audio transformer system including multi-circuit modules and rack mount equipment chassis is also provided.

Complex high frequency components

Abstract: The present invention comprises baluns 2a, 2b which convert balanced line signals and unbalanced line signals mutually, and filters 3a, 3b which are electrically connected to the baluns 2a, 2b and pass or attenuate the predetermined frequency bands. Electrode layers 15a-22a, 25a, 41, 42, 43 which compose the electrode patterns of the baluns 2a, 2b and the filters 3a, 3b, and the dielectric layers 30-39 are integrally stacked.