Compact Balun Research Articles

High-Efficiency 200-GHz Neutralized Common-Base Power Amplifiers in 250-nm InP HBT

The analysis, design, and measurement of two Indium Phosphide (InP) heterojunction bipolar transistor (HBT) power amplifier (PA) designs are presented at G-band with record efficiency. A pseudo-differential common-base (CB) stage with neutralization capacitors and low-loss coupled-line balun (CLB) improve the gain and reduce matching loss. A single-stage design achieves 8.3 to 12.7-dBm output power and 7.7 to 17.3% power-added efficiency (PAE) over 180 to 220 GHz. The use of compact baluns allows the design to occupy only 0.011mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with power density of 1.69 W/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . A 3-stage, 4-way power-combined PA delivers 16.6 to 19.7-dBm output power and 6.5 to 13% PAE over 185 to 210 GHz.

A 10 GHz Compact Balun with Common Inductor on CMOS Process

This paper presents a compact balun with a common inductor design. The design used Wilkinson-type balun topology with modified lumped transmission lines and a common inductor to realize circuit size reduction on a lossy CMOS process. Measurements of the prototype chip had a reflection coefficient below 17.8 dB at all ports, an insertion loss of 1.98 dB, and an isolation of 16.8 dB. The chip size was only 0.025λ0 × 0.034λ0.

Integration Design of Compact Balun Filters and Duplexing Balun Filter With Arbitrary Frequency-Selective Response

Integration Design of Compact Balun Filters and Duplexing Balun Filter With Arbitrary Frequency-Selective Response

Compact Dual-Mode Balun Bandpass Filter with Improved Out-of-Band Performance

A compact dual-mode balun bandpass filter with improved out-of-band performance is proposed based on a ring resonator. In order to excite the two degenerate modes and obtain filtering balun performance, three parallel-coupled lines are placed at three excitation ports along the ring resonator. By properly arranging the angles between the excitation arms, four transmission zeros can be realized to improve stopband performance. Finally, a prototype of the designed balun bandpass filter is implemented and fabricated. The measured results show a good agreement with those obtained from the simulation, thus verifying our proposal with good in-band filtering and out-of-band performance.

SIZE REDUCTION OF KLOPFENSTEIN-BALUN TRANSFORMER FOR BALANCED ANTENNAS

A BALUN transformer converts impedance into another one and also converts an unbalanced line into a balanced line. A compact size broadband BALUN transformer is designed using Klopfenstein taper line transformer approach to transform 50Ω impedance into 100 Ω. The results of the conventional BALUN are compared with the proposed compact size BALUN. In order to reduce the length of the BALUN, a curved microstrip line is used. The proposed compact size BALUN is 56 %- 70 % smaller in size w.r.t the conventional BALUN but at the cost of 6% - 11% reduction in the overall band. The conventional BALUN has measured % bandwidth of 165 while the reduced size BALUN has 159. The measured results are in agreement with the simulated results.

A tightly coupled dipole array used for radiation power improvement on finite radiation aperture

Radiation power of an electromagnetic wave plays a decisive role in its transmission distance. Traditionally, the radiation power can be improved by expanding the radiation aperture size of the antenna array or increasing input power of the unit cell. However, the radiation aperture size is always restricted by assembly space. The input power improvement of the unit cell is always limited by the signal source. It is difficult to improve radiation power on a finite radiation aperture. However, the radiation power on a finite radiation aperture is related closely to the number of antenna elements and the radiation efficiency of the antenna array. It is useful to arrange more elements and improve radiation efficiency of the antenna array to improve the radiation power on a finite radiation aperture. Wideband wide-angle scanning phased array is able to make full use of a finite radiation aperture. The wide-angle scanning properties make it possible for the radiated power to cover a wide area. In this paper, a compact wideband wide-angle scanning tightly coupled dipole array (TCDA) is proposed. A high permittivity substrate and compact wideband balun are used for miniaturizing the antenna array. The period of the unit cell is only 0.144&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;high&lt;/sub&gt; × 0.144&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;high&lt;/sub&gt; (&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;high&lt;/sub&gt; is the wavelength at the highest operation frequency in free space). Parameters of the balun are optimized to improve impedance matching between the balun and the antenna array. Two bilateral frequency selective surfaces (FSSs) are used to replace traditional dielectric superstrate to improve the impedance matching between the antenna array and free space. A low-loss dielectric substrate is used to reduce dielectric loss of the antenna array. In these ways, the radiation efficiency is greatly improved. The simulation results show that the proposed antenna array operates at 1.7–5.4 GHz (3.2:1) while scanning up to 65° in the E plane, 45° in the H plane and 60° in the D plane with following a rigorous impedance matching criterion (active VSWR &lt; 2). A 16 × 16 prototype array is fabricated and measured. Good agreement is achieved between the simulation results and the measurement results. Compared with the designs in the literature, the proposed antenna array has an excellent performance in radiation power on a finite radiation aperture.

A UHF Compact Complex Impedance-transforming Balun with High Isolation

Background: A compact complex impedance-transforming balun for UHF frequencies, which is based on a coupled-line structure that matched all ports and provided high output port isolation, was designed in this paper. Methods: A lumped component transformation was used to minimize circuit size. The implemented circuit operated at 433 MHz with the reflection coefficients less than -16 dB at all ports, 0.22 dB amplitude balance and 180° phase balance at the output ports. The signal coupling between the output ports was -16.8 dB. The circuit size is small at 0.032λ. Results: Complex impedance-transforming baluns were designed to operate at 433 MHz. The source impedance at port 1 was set at Zs = 12 - j12Ω and the load impedances at port 2 and 3 were set at ZL = 80 + j30Ω. Conclusion: A compact complex impedance-transforming balun at UHF frequency, with all ports matched and high isolations, was designed and illustrated in this paper.

Analysis and implementation of compact two-section half-wave balun using artificial transmission lines

ABSTRACTIn this paper, a compact two-section half-wave balun using artificial transmission lines is proposed. This paper describes design rules that need to be satisfied for a two-section half-wave balun by the even- and odd-mode analysis. According to the design rules, a two-section half-wave balun using microstrip lines is designed and simulated. Then, to reduce dimensions, conventional quarter-wavelength microstrip transmission lines are replaced by artificial transmission lines realized by a series of meandered-line inductors, parallel-plate capactiors, and interdigital capacitors. Additionally, the improved artificial transmission lines with chip capacitors have realized lines with very low characteristic impedance that cannot be easily achieved by conventional transmission lines. Based on these theories, a two-section half-wave balun using artificial transmission lines has been designed and fabricated. The developed balun occupies 25.1 mm × 20.2 mm, which almost equals to 5.0% of this topology of balun adopting conventional microstrip transmission lines. The simulated and measured results demonstrate good agreements between them, which verifies feasibility of the proposed designing method.

Design of a multiband ground radiation antenna by utilizing balun excitation

AbstractThe design and performance of a triple‐band ground radiation antenna with a compact balun are shown in this paper. A microstrip balun is integrated with a modified rectangular ground plane has provided wideband frequency characteristics. With the help of the theory of the characteristic mode, the resonance phenomenon of the rectangular ground plane is analyzed. An eight‐like‐loop slit is embedded in the ground plane to excite multiple resonant modes. In, addition, by etching two rectangular slots at two terminals of the eight‐like‐loop slit, the capacitance of the ground‐plane resonator decreases such that the impedance‐matching condition in the upper‐frequency band can be improved. Finally, a triple‐band frequency performance is derived by embedding a simple matching circuit. The proposed antenna achieves the measured impedance bandwidths from 1.02 to 1.06, from 1.35 to 1.62, and from 1.96 to 2.55 GHz. The simulated current distributions of a ground‐plane prototype are also experimentally verified.

Design and validation of miniaturize Rat Race Coupler based microstrip Balun

This work presents a compact Balun with enhanced bandwidth and better isolation between output ports using Interdigital Capacitor (IDC). Firstly, a Rat Race Coupler (RRC) is designed, later Balun is proposed by replacing the isolation port with a 50 Ω isolation resistor. The proposed Transmission line (TL) is designed using an IDC in parallel with a high impedance TL. Based on a π-equivalent circuit the proposed TL has been investigated and optimized to achieve 70.7 Ω impedance. The Balun is designed and fabricated. The simulated and fabricated results are in accord. The fractional bandwidth (FBW) of RRC and Balun are 37.5% and 33% respectively at centre frequency 2.4 GHz. The size occupied by the proposed Balun is 0.51λg × 0.22λg. The structure is low cost, uniplanar and compact.

Comment and response on "A Compact Single-Stage Balun" [Backscatter

Comment and response on "A Compact Single-Stage Balun" [Backscatter

A Compact SISL Balun Using Compensated Interdigital Capacitor

This letter proposes a compact self-packaged balun using compensated interdigital capacitor (CIDC) based on substrate integrated suspended line (SISL) platform. Compared with traditional single-layer interdigital capacitor or parallel-plate capacitor, CIDC has higher capacitance density and thus the circuit size can be reduced. Using the CIDC, a compact SISL balun based on a modified second-order lattice balun topology is designed and fabricated using the standard printed circuit board process. The measurement results agree well with the simulation ones, which shows that within 66.7% bandwidth, the measured amplitude imbalance and phase imbalance are ±0.89 dB and 181 ± 1.4°, respectively. A compact circuit size of $0.06~\lambda \text{g} \,\, \times 0.11~\lambda \text{g}$ is achieved.

Planar compact dual-band coupled-line balun with high isolation

A planar circuit structure, which is based on three cascaded pairs of coupled lines, an open stub, and an isolation resistor, is proposed in this paper to design a compact dual-band balun with high isolation. This circuit features equal power division with out of phase, all ports matching, high isolation between two outputs, compact structure, and inherent impedance transformation. The closedform design equations are derived based on the traditional transmission-line theory and even-(odd-) mode analysis. A practical dual- band balun, which operates at 0.9/1.8GHz, is designed and fabricated to validate the function of equal power division with out of phase and high isolation between two outputs. The consistency between the simulated and measured results verify the design theory.

Planar Compact Dual-Band Balun with Flexible Frequency Ratios

ABSTRACTIn this article, a planar coupled-line circuit configuration is proposed to design a compact dual-band balun with flexible frequency ratios. This balun, which is based on the symmetrical four-port circuit with one port open, essentially consists of two pairs of coupled lines and a tapped open stub. Closed-form solutions are derived using the even- and odd-mode analytical methods and wide frequency ratios (2.3 < g < 4.2) are obtained. Meanwhile, a practical experiment operating at 0.9/1.75 GHz simultaneously, of which the size is only 0.02 λ2g, is designed and fabricated. The agreements between the simulated and measured results verify our design theory.

Interview

Dr Jianpeng Wang, from the Nanjing University of Science and Technology in China, talks about the work reported in their Letter ‘Compact microstrip balun diplexer using stub-loaded dual-mode resonators’, page 1994. Dr Jianpeng Wang As is well known, dual-band operation is frequently demanded in transceiver modules of modern wireless microwave communication systems. Rather than arranging two separated frequency-selective radio frequency (RF) circuits in the systems, many researchers choose an independent device, i.e., the diplexer, to support such systems. This is a useful component for reducing the overall size of RF transceiver applications. Microstrip diplexers are a three-port passive devices, which have the capability to split common input signals into two individual output streams operating in different frequency bands with high port-to-port isolation. The involved stub-loaded resonators in our design are the typical form of the dual-mode resonator. Their resonant properties have been characterised by using the even-odd mode analysis method. Through this method, we can examine how, by properly adjusting the length of the loaded stub, the even-mode resonant frequency of the dual-mode resonator can be tuned, while keeping the odd-mode resonant frequency almost unchanged. In this context, two resonant frequencies generated by the employed stub-loaded resonator can be flexibly controlled to realise a dual-mode response, which will substantially decrease the size of the balun diplexer, making it preferable to single mode resonators. In general, the utilised resonators play an important role in the implementation of compact balun diplexers with a certain bandwidth and two transmission poles in each operating band. What makes our work unique is the implementation of a typical multi-function integrated component, which effectively simplifies the circuit design, and reduces the overall size of radio frequency (RF) transceiver front-end systems. During the design phase, each balun filter channel in the diplexer can be independently controlled without effecting others, thus showing greater flexibility. Furthermore, no additional T-junction or matching networks are demanded at the common input port in our balun diplexer design. In our Electronics Letters paper, we introduced a new microstrip unbalanced-to-balanced (balun) diplexer, which utilises the stub-loaded dual-mode resonators. The proposed diplexer consists primarily of two balun filter channels. Meanwhile, these two balun filter channels are directly connected through a common open-circuited half-wavelength transmission line without any additional matching network. This unique property will reduce the overall size compared with other diplexer circuits using T-junction for the purpose of impedance matching. By adopting this method, we can create a compact, high performance balun diplexer with a remarkably simple structure. These changes are meaningful for RF engineers who design multi-function embedded unbalanced-to-balanced feeding networks in modern dual-band wireless communication systems. The presented design concept is a worthy guideline for the implementation of multi-function embedded passive components. In short, compared with the current approaches, it is more desirable to develop multi-function embedded components based on the viewpoints of explicit operation principles, simple structures, and high performances. In this way, these components can really facilitate and simplify RF transceiver front-end systems. It is our belief that components or systems using these techniques will prove more valuable to the engineering community.

Синтез компактных широкополосных согласующе-симметрирующих устройств на отрезках связанных линий передачи

Синтез компактных широкополосных согласующе-симметрирующих устройств на отрезках связанных линий передачи

Wideband Dual-Polarized Printed Dipole Antenna Using Differential Feed

A novel wideband dual-polarized printed dipole antenna fed by two integrated feeding networks is presented. The feeding network, a kind of compact halfwave balun, delivers equal amplitude (within 0.1 dB) and 180° (±5°) phase difference between the two output ports from 1.65 to 2.8 GHz. By employing an H-shaped slot in each arm of the dipole, wide impedance bandwidth has been obtained. Experimental results show that the proposed antenna can operate from 1.7 to 2.7 GHz with low voltage standing wave ratios (<1.5) at the two ports. Low cross-polarization (>25 dB) and high isolation (>31 dB) are also achieved over the entire bandwidth. Moreover, stable radiation patterns and low back lobes are obtained by using a modified reflector.

A new compact ultra-wideband balun for printed balanced antennas

A new ultra-wideband balun and its application for balanced antenna are presented in this paper. To realize the balun-type function, two different types of microstrip to slotline transition forms are adopted for the unbalanced and balanced outputs of the balun. Further, an ultra-wideband balun and its integration with a Vivaldi antenna are designed and fabricated to validate the feasibility of the new approach. Results indicated that the proposed balun and the antenna can operate from 3.6 to 10.7 GHz. For the proposed new balun, it exhibits a good balanced performance of within 0.5 dB magnitude imbalance and less than 6° phase imbalance between the two balanced outputs. Meanwhile, the antenna reveals good unidirectional radiation patterns.

Compact Two-Section Half-Wave Balun Based on Planar Artificial Transmission Lines

Artificial transmission lines are realized by a series of meandered-line inductors, parallel-plate capacitors, and interdigital capacitors, which belong to metamaterial transmission lines. An ameliorated artificial transmission line is proposed to realize a low characteristic impedance transmission line. A two-section half-wave balun at 900 MHz is designed, fabricated, and measured in this paper. The compact balun is based on conventional and ameliorated planar artificial transmission lines instead of microstrip transmission lines. The main advantage of the proposed balun is its size reduction, which occupies only about 10% of a conventional one. Measured results match well with theory and simulation. The balun features excellent amplitude and phase balance in microwave power combining and a reasonable bandwidth of the return loss as well.

A Novel Compact Balun Using a Weakly Coupled Line With Grounded Resonator

A compact balun is proposed using a very weakly coupled line loaded with a parallel resonator. Based on an equivalent circuit model, the balun behaves as a matching network for odd-mode operation and a bandstop circuit for even-mode operation. The proposed balun can exhibit a broad bandwidth from 2.4 to 3.6 GHz with return loss of S 11 below 10 dB. This balun provides only 0.1 dB amplitude difference and gives 180 ° ±5 ° of phase difference between S 21 and S 31. The electrical size is only 0.088 λg ×0.078 λg and fractional bandwith is 40%. Different from previous broadband baluns, the proposed balun can be implemented in low coupling-coefficient structures, which means complex strongly coupled lines (more than two wires) aren't required. This idea is one of the main reasons to achieve a very compact balun.