A new wide-band planar balun on a single-layer PCB

A new wide-band microstrip balun implemented on a single-layer printed circuit board (PCB) is presented in this letter. The proposed planar balun consists of a wide-band Wilkinson power divider and a noncoupled-line broad-band 180/spl deg/ phase shifter. To demonstrate the design methodology, one prototype is realized. The new design was simulated and validated by the measurement. Measured results show that 10-dB return loss of the unbalanced port has been achieved across the bandwidth from 1.7 GHz to 3.3 GHz, or 64%. Within the operation band, the measured return losses for both the two balanced ports are better than -10 dB, and the balanced ports isolation is below -1.5 dB. The measured amplitude and phase imbalance between the two balanced ports are within 0.3 dB and /spl plusmn/5/spl deg/, respectively, over the operating frequency band.     

Compact 28-GHz subharmonically pumped resistive mixer MMIC using a lumped-element high-pass/band-pass balun

This work reports a novel lump-element balun for use in a miniature monolithic subharmonically pumped resistive mixer (SPRM) microwave monolithic integrated circuit. The proposed balun is simply analogous to the traditional Marchand balun. The coupled transmission lines are replaced by lump elements, significantly reducing the size of the balun. This balun requires no complicated three-dimensional electromagnetic simulations, multilayers or suspended substrate techniques; therefore, the design parameters are easily calculated. A 2.4-GHz balun is demonstrated using printed circuit board technology. The measurements show that the outputs of balun with high-pass and band-pass responses, a 1-dB gain balance, and a 5/spl deg/ phase balance from 1.7 to 2.45 GHz. The balun was then applied in the design of a 28-GHz monolithic SPRM. The measured conversion loss of the mixer was less than 11dB at a radio frequency (RF) bandwidth of 27.5-28.5 GHz at a fixed 1 GHz IF, a local oscillator (LO)-RF isolation of over 35 dB, and a 1-dB compression point higher than 9 dBm. The chip area of the mixer is less than 2.0 mm/sup 2/.     

A Wide-Band Parallel-Connected Balun

It is pointed out that parallel-connected baluns (4:1 impedance transformation) have approximately four times the operating bandwidth of series-connected baluns (1:1 impedance transformation). The simple theory of uncompensated resonant baluns is discussed, and design curves are presented which may be used to design any balun of this type. Experimental results are given on one type of parallel-connected balun showing it capable of a 25:1 operating bandwidth as predicted by theory. Operating over this bandwidth, the balun is only /spl lambda/ / 25 in length at the lower band-edge frequency. Because of its 4:1 impedance transformation, the balun should be very useful in the feeding of frequency-independent antennas with high impedance, such as the conical spiral.     

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

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 0.5 dB and phase balance of less than 5/spl deg/ from 1.2 to 3.2 GHz.     

Chip-type LTCC-MLC baluns using the stepped impedance method

A chip-type low-temperature co-fired ceramic (LTCC) multilayer ceramic (MLC) balun is presented in this paper. This balun is designed using the stepped impedance method. It uses a multilayer structure, meander lines, and multisection coupled lines. The use of multisection couple lines that have various characteristic impedance ratios can shrink the length of a quarter-wavelength coupled-transmission line and makes it very easy to match various impedances of balanced output. The proposed chip-type balun operates over a bandwidth of 2.25-2.65 GHz. The in-band phase and amplitude balances are excellent because of the symmetric structure and transmission-line trimming section. Measured results of the chip-type LTCC-MLC balun match well with the computer simulation     

A silicon monolithic spiral transmission line balun withsymmetrical design

In this work, a spiral transmission line balun has been fabricated on a high resistivity silicon substrate. The Marchand-type balun has been designed to have the same physical common ground points for the output transmission lines, which eliminates imbalance due to potential difference at the ground. Return loss is better than 17 dB in the frequency band of 1.6-4.1 GHz, especially 39 dB around 1.9 GHz. The amplitude imbalance is less than 0.3 dB throughout the bandwidth. The phase departure from 180° is less than 20 over the frequency range of 1.6-2.6 GHz. The balun is suitable for MMIC application     

A novel planar dual balun for Doubly Balanced star mixer

A novel planar dual balun for doubly balanced star mixer is presented. The balun consists of two identical Marchand baluns using coupled microstrip lines. It shows the amplitude imbalance within 1.2 dB and the phase imbalance within 180/spl plusmn/1.5/spl deg/ over 1.2 to 2.8 GHz. The star mixer using a pair of the suggested balun has the conversion loss about 6 dB in the band.     

Design of an ultra compact electronically tunable microwave impedance transformer

A novel ultra compact microwave tuneable impedance transformer topology is proposed. It consists of a classical /spl pi/ CLC network where an equivalent tuneable inductance is realised with a high impedance transmission line in series with fixed inductance and a diode's varactors. The realised hybrid prototype at 900 MHz operating frequency is only 0.06/spl lambda/-long. Impedance loads from 16.5 to 280 /spl Omega/ can be matched with a return loss better than -20 dB, and the relative bandwidth equals /spl plusmn/36% for a fixed 50 /spl Omega/ load.     

一种无需接地结构的巴伦设计

研究了一种新型的耦合线巴伦结构的设计。该巴伦结构简单,仅包含一对耦合线和一根独立传输线,可在单层PCB板上实现,无需任何接地结构。文中给出了该巴伦的设计公式,并分析了在不同端口阻抗比情况下理想电路的阻抗取值范围。该结构中设计参数灵活,还可以通过改变传输线的阻抗值来调整工作带宽。此外,从设计公式中可看到这种结构也很适合设计具有较大的端口阻抗比的巴伦。文中对设计进行了实物样品加工,其工作频率为1.5GHz。其测试结果与理想电路、三维仿真曲线都很吻合。     

Analytical Model of the Split-Coaxial Balun and Its Application to a Linearly-Polarized Dipole or a CP Turnstile

A simple analytical transmission line model of a split-coaxial balun is proposed and tested. It is based on the coupled symmetric transmission line approach. The model leads to a closed-form analytical expression for the termination impedance/transfer function of the complete antenna system that includes antenna, balun, and a non-splitted coaxial line of certain length. It accepts the impedance of a center-fed symmetric antenna as input parameter. The model is in excellent agreement with full wave simulations and is confirmed by a series of prototype measurements. It can be applied to a linearly-polarized radiator or to a broadband circularly-polarized turnstile, where the phase quadrature is created by two complex-conjugate impedances. The present model only describes the impedance matching properties of the balun but is not capable of predicting the balance quality of baluns.     

A Miniaturized Multilayered Marchand Balun Using Coupled Artificial Transmission Lines

A miniaturized Marchand balun is investigated in this letter. The Marchand balun is realized on a six-layered printed circuit board by integration of two coupled artificial transmission line sections. An additional artificial line is inserted in-between the coupled lines for compensating the asymmetry. With the help of the even odd mode analysis, the electrical characteristics of the coupled lines are investigated in detail. The proposed balun has the smallest occupied size among the previous designs on printed circuit boards. It features excellent amplitude and phase imbalance, and a comparable return loss bandwidth as well. The design methodology, simulation, and experimental results are introduced thoroughly in the letter.      

Optimum Design of Wideband Compensated and Uncompensated Marchand Baluns With Step Transformers

This paper presents a design approach for wideband compensated and uncompensated Marchand baluns with stepped-impedance transformers. In order to obtain an equal-ripple bandpass response, conventional Chebyshev polynomials are modified to compensate the effect of the transfer function's dc poles. Unlike the available microwave filter design approaches, which usually require redundant elements, this approach leads to an optimum design by using the minimum number of equal length transmission line elements. Based on this design approach, both compensated and uncompensated Marchand baluns are studied. It is found that increasing difficulty arises when implementing a large bandwidth balun using the widely adopted compensated balun structure. Hence, the uncompensated balun structure becomes a better choice. To validate the proposed design approach, an uncompensated balun is designed on a standard two-sided printed circuit board. The measured results indicate that a return loss greater than 20 dB can be observed from 1 to 7.5 GHz. The phase imbalance is less than 4° and the amplitude is less than 0.5 dB from dc to 7.2 GHz.      

Low-Loss and Broadband Asymmetric Broadside-Coupled Balun for Mixer Design in 0.18-$mu{hbox {m}}$ CMOS Technology

This study presents an asymmetric broadside coupled balun with low-loss broadband characteristics for mixer designs. The correlation between balun impedance and a 3D multilayer CMOS structure are discussed and analyzed. Two asymmetric multilayer meander coupled lines are adopted to implement the baluns. Three balanced mixers that comprise three miniature asymmetric broadside coupled Marchand baluns are implemented to demonstrate the applicability to MOS technology. Both a single and dual balun occupy an area of only 0.06 mm². The balun achieves a measured bandwidth of over 120%, an insertion loss of better than 4.1 dB (3 dB for an ideal balun) at the center frequency, an amplitude imbalance of less than 1 dB, and a phase imbalance of less than 5deg from 10 to 60 GHz. The first demonstrated circuit is a Ku-band mixer, which is implemented with a miniaturized balun to reduce the chip area by 80%. This 17-GHz mixer yields a conversion loss of better than 6.8 dB with a chip size of 0.24 mm². The second circuit is a 15-60-GHz broadband single-balanced mixer, which achieves a conversion loss of better than 15 dB and occupies a chip area of 0.24 mm². A three-conductor miniaturized dual balun is then developed for use in the third mixer. This star mixer incorporates two miniature dual baluns to achieve a conversion loss of better than 15 dB from 27 to 54 GHz, and occupies a chip area of 0.34 mm².     

Microstrip Balun Over High Impedance Wire-Ground

This letter presents a novel idea for the design of coupled line balun, where the operation relies on rejecting the common mode due to the presence of a high impedance wire-ground. This concept is verified by circuit modeling, EM simulations, and practical measurements of the proposed structure. The simple, though accurate, circuit model provides clear understanding of the concept of operation and simplifies the design flow and optimization. The novel design exhibits reliable performance at 2.4 GHz with a 50% bandwidth (1.8–3 GHz), an amplitude imbalance less than 0.5 dB, a return loss better than 15 dB, and a phase imbalance less than 10$^{circ}$.      

A Highly Compact Active Wideband Balun With Impedance Transformation in SiGe BiCMOS

A new conveyor-based single-ended to differential balun is proposed. Thanks to the quasi-absence of passive components, this is an extremely size-efficient balun (0.036 ). The use of a new impedance-matching technique makes this balun the first transistor-based solution with controllable port impedances. Fabricated in a 0.35-mum SiGe BiCMOS technology with f_T=45 GHz, the balun shows the following performance: wideband impedance matching at all three ports, good balance between the two outputs (better than 3 dB in amplitude and 13deg in phase) over frequency bands extending from 0 to 3 GHz, linear operation for powers up to input powers of -2 dBm, and stability against temperature and process variations.     

低成本宽带90°巴伦的研究与设计

提出并设计了一种低成本宽带90°巴伦电路结构,电路由宽带耦合威尔金森功分器、弱耦合线和扇形阶跃阻抗谐振器级联的宽带90°移相器组成。利用电磁仿真软件HFSS对工作在中心频率为1.65GHz 的微带电路进行建模和仿真。采用PCB工艺制作了电路实物并利用矢量网络分析仪进行测试;对比得出仿真与测试结果十分吻合,该巴伦实测相对带宽大于117.0% (0.65～2.58GHz),带内各端口回波损耗好于12.6 dB,输出端口隔离度大于13.1dB,带内插入损耗小于0.5 dB,相位误差小于90°±7.6°。与现有的结构和设计相比,该巴伦不仅具有更大的工作频带和单层电路布局,而且具有容易加工、成本低的优点。     

A 2-bit miniature X-band MEMS phase shifter

The design and performance of a compact low-loss X-band true-time-delay (TTD) MEMS phase shifter fabricated on 8-mil GaAs substrate is described. A semi-lumped approach using microstrip transmission lines and metal-insulator-metal (MIM) capacitors is employed for the delay lines in order to both reduce circuit size as well as avoid the high insertion loss found in typical miniaturized designs. The 2-bit phase shifter achieved an average insertion loss of -0.70 dB at 9.45 GHz, and an associated phase accuracy of /spl plusmn/1.3/spl deg/. It occupies an area of only 5 mm/sup 2/, which is 44% the area of the smallest known X-band MEMS phase shifter . The phase shifter operates over 6-14 GHz with a return loss of better than -14 dB.     

LTCC-MLC chip-type balun realised by LC resonance method

A multilayer ceramic balun designed in the 2.4 GHz ISM band frequency is presented. A multilayer structure to realise the low temperature co-fired ceramic (LTCC) balun is proposed. This type of balun comprises an embedded capacitor and meandered or spiral coupled lines. The use of an LC resonator can shrink the length of a coupled transmission line and can be designed very easily to have various balanced output port impedances. Excellent performance of phase and amplitude balance may be achieved by the proposed method. Measured results of the LTCC-multilayer ceramic (MLC) balun match well with the computer simulation     

Broadband circularly polarized rectangular loop antenna with impedance matching

A broadband circularly polarized rectangular loop antenna is developed. The broadband performance is achieved by adding a pair of parasitic loops inside the rectangular loop. Good impedance matching is obtained by introducing a broadband balun. The proposed rectangular loop has a bandwidth of 46% for axial ratio/spl les/2dB and 50% for VSWR/spl les/2 with a gain of around 8dBi.     

InAs HEMT narrowband amplifier with ultra-low power dissipation

The design, fabrication and performance of a prototype narrowband amplifier using InAs-channel HEMTs are reported. The amplifier, which is realised on an RT/Duroid circuit board with a combination of transmission lines and lumped components, is intended for a long-life battery-powered application. The two-stage amplifier has 20 dB of gain with a bandwidth of 4% in S-band and dissipates a total power of only 365 /spl mu/W.