Inductively Compensated Parallel Coupled Microstrip Lines and Their Applications

A simple method using lumped inductors to compensate unequal even- and odd-mode phase velocities in parallel coupled microstrip lines is presented. The singly and doubly compensated cases are analyzed to enable the optimum inductor values and the electrical lengths of the compensated coupled lines to be calculated from closed-form expressions. The technique proposed not only improves the performance, but also yields a more compact design. To demonstrate the technique's broad range of applicability, the compensated coupled-line structure is used to enhance the performance of a 900-MHz Lange coupler, a 1-GHz multisection 10-dB coupler, a 900-MHz planar Marchand balun, and a 1.8-GHz parallel coupled bandpass filter.     

微带巴伦设计

根据微带耦合线的准TEM模参数 ,推导出相同耦合线Marchand巴伦须满足的导纳方程 ,讨论了改善巴伦性能的方法———电容补偿法。ADS仿真结果表明 :采用最佳条件选取的耦合线 ,巴伦的反射系数接近最小 ,传递系数接近最大 ;采取电容补偿后 ,可进一步改善巴伦的性能。最后给出宽边耦合线巴伦的实验结果。结果表明 :可用上述导纳方程设计巴伦耦合线的参数。     

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.      

A Dual-Band Balun Using Partially Coupled Stepped-Impedance Coupled-Line Resonators

In this paper, a recently proposed dual-band resonator structure consisting of a pair of partially coupled stepped-impedance lines is theoretically investigated. The new resonator configuration contains a number of attractive features for dual-band applications. A new type of dual-band balun that is constructed using a pair of such coupled stepped-impedance resonators is fully studied both theoretically and experimentally. Design equations for the balun are derived by an even- and odd-mode approach. A prototype of such dual-band balun operating at 900 MHz and 1.8 GHz is designed, fabricated, and measured. Good agreement between the designed and measured responses proves the concept of the dual-band balun and validates the design formulas.     

Design Equations for an Interdigitated Directional Coupler (Short Papers)

General design equations for an interdigitated directional coupler are derived. The design equations are written in terms of even- and odd-mode admittances for a pair of coupled lines which are identical to any pair of adjacent lines in the coupler. The calculated values of even- and odd-mode admittances can be translated into a physical configuration from published data on coupled lines.     

Analysis and design of impedance-transforming planar Marchandbaluns

A technique for designing impedance-transforming baluns is presented in this paper. It is based on the Marchand balun with two identical coupled lines. By varying the coupling factor of the coupled sections, a wide range of impedance transforming ratios can be achieved. In addition, a resistive network added between the balun outputs is proposed to achieve balun output matching and isolation. Microstrip baluns, matched at all ports, for transforming from a 50-Ω source impedance to 40-Ω as well as 160-Ω load terminations are realized to demonstrate the technique     

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.     

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.     

A Miniature Q-Band Balanced Sub-Harmonically Pumped Image Rejection Mixer

This work presents a miniature Q-band balanced single side-band sub-harmonically pumped image rejection diode mixer (SHIRM) using a compact Marchand dual balun design. The SHIRM is realized employing four anti-parallel diode pairs for frequency mixing, a Lange coupler for radio frequency (RF) signal input, and a reduced size three-conductor-line Marchand dual balun for local oscillator pumping. The length of three-conductor-line dual balun is reduced by 81% after shunting two lumped capacitors at the center conductor. The measured results exhibit a minimum conversion loss of 8.6 dB, a maximum image rejection ratio of 22 dB, all ports isolation better than 37 dB, and an input 1-dB compression point of 2.5 dBm at RF bandwidth of 40.5 to 43.5 GHz and fixed intermediate frequency of 2.4 GHz. The chip area is very compact, only 1 times 0.84mm²     

Spiral transmission-line baluns for RF multichip module packages

We describe a design method and lumped model for a circular spiral transmission-line balun. All lumped values are extracted from the geometric parameters of the balun. From simulation, the design parameters with well predicted characteristics are defined. The balun is fabricated using multi-chip module processing technology, which is suitable for integration in RF packages. Measurements show a wide bandwidth of 1.5-4.1 GHz and excellent balanced outputs. Amplitude imbalance less than 0.5 dB and phase imbalance less than 4° are achieved. The simulation results are compared with the measurement. The model captures all important properties of the balun with reasonably high accuracy     

Exact Synthesis of Broadband Three-Line Baluns

Three types of three-line baluns are studied in this paper. The equivalent circuits of these baluns are derived using the model of coupled transmission lines. The balun designs with Chebyshev response can then be exactly synthesized. A complete design procedure of the baluns with second-, third-, and fourth-order insertion loss functions is presented. Balun designs with wide bandwidths of more than 2 to 1 are achievable by this method. Some guidelines for practical realization are also suggested. A third-order balun design with a fractional bandwidth of 80% is given to demonstrate the proposed procedure.     

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/.     

Design and Analysis of Millimeter-Wave Marchand Balun with Interconnected Transmission Line

This paper presents the design and analysis of general baluns of Marchand-type with a transmission line connected between two sections. A series of new expressions of S-parameters are derived for such type of Marchand balun. The relations between the length of interconnected transmission line and the imbalance of Marchand balun are discussed. By using analytical method, a millimeter-wave Marchand balun was designed and simulated by the full-wave electromagnetic software HFSS, and fabricated in 0.15 μm pHEMT GaAs process. The measurement results show that the balun achieves low insertion loss and good balance in the band of 24–40 GHz. The results are in good agreement with the simulated ones. The theoretical analysis is verified.     

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.     

一种小型化带通滤波微带巴伦设计

提出一种小型化带通滤波微带巴伦的设计。在Marchand巴伦的基础上,使用一个半波长和两个1/4波长传输线作为谐振器,在带通滤波微带巴伦的两个输出端口可以获得相同幅度和相反相位的平衡信号。利用谐振器平行线耦合可以观察到通带两侧存在两个传输零点。对提出的中心工作频率在2.65 GHz的带通滤波微带巴伦进行了实物加工与测试。两个输出端口信号幅度差与相位差分别为±0.4 dB和180°±5°。仿真与测量结果有较好的一致性,验证了本文所提方案的可行性。     

Analysis and Design of Reduced-Size Marchand Rat-Race Hybrid for Millimeter-Wave Compact Balanced Mixers in 130-nm CMOS Process

The analysis and design flow for reduced-size Marchand rat-race hybrids are presented in this paper. A simplified single-to-differential mode is used to analyze the Marchand balun, and the methodology to reduce the size of Marchand balun is developed. The 60-GHz CMOS singly balanced gate mixer and diode mixer using the reduced-size Marchand rat-race hybrid are implemented to verify the design methodology. The monolithic microwave integrated circuit mixers achieve comparable performance with a compact chip size among the reported 60-GHz CMOS mixers.      

Using buried capacitor in LTCC-MLC balun

A novel chip-type ceramic balun designed in the 2.4 GHz ISM band frequency is presented. A buried capacitor is included in the balun, so that the length of the coupled transmission lines can be reduced and can be designed very easily. A meander or spiral broadside coupled-line is adopted to realise the proposed LTCC multi-layer balun. The measured performances of phase and amplitude balance for this LTCC-MLC balun show a good match with computer simulation     

Analysis and synthesis of coplanar coupled lines on substrates offinite thicknesses

This paper presents two sets of newly developed CAD-oriented formulas for the evaluation of the quasi-static even and odd-mode characteristics of coplanar coupled lines on substrates of finite thicknesses. The first set of expressions is derived based on the conformal mapping method. Numerical results show that both the even- and odd-mode characteristic impedances and effective dielectric constants computed by these expressions are in good agreement with the results generated by the spectral domain method. The second set of formulas is derived based on a seminumerical approach and can be used to calculate the geometrical parameters of coplanar coupled lines directly from the given electrical parameters, without using an iterative approach. These seminumerical formulas give maximum error in impedance calculation of about 2.0% (c/h<2), over a wide range of impedance and dielectric constant values     

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.      

Compact and broad-band three-dimensional MMIC balun

This paper presents a simple and effective technique which compensates for the amplitude and phase differences of the Marchand balun. Compensation is accomplished by interconnecting a short transmission line to a pair of couplers. As a result, Marchand balun with operation frequency ranging as wide as 8.2-30 GHz is achieved. To fabricate the prototype, we adopt three-dimensional monolithic-microwave integrated-circuit technology together with a 2.5 μm×4 layer polyimide structure stacked over a GaAs wafer. The topology yields a circuit area as small as 0.2 mm×0.4 mm for the balun