High‐Efficiency CMOS Power Amplifier Using Uneven Bias for Wireless LAN Application

This paper proposes a high‐efficiency power amplifier (PA) with uneven bias. The proposed amplifier consists of a driver amplifier, power stages of the main amplifier with class AB bias, and an auxiliary amplifier with class C bias. Unlike other CMOS PAs, the amplifier adopts a current‐mode transformer‐based combiner to reduce the output stage loss and size. As a result, the amplifier can improve the efficiency and reduce the quiescent current. The fully integrated CMOS PA is implemented using the commercial Taiwan Semiconductor Manufacturing Company 0.18‐μm RF‐CMOS process with a supply voltage of 3.3 V. The measured gain, P_1dB, and efficiency at P_1dB are 29 dB, 28.1 dBm, and 37.9%, respectively. When the PA is tested with 54 Mbps of an 802.11g WLAN orthogonal frequency division multiplexing signal, a 25‐dB error vector magnitude compliant output power of 22 dBm and a 21.5% efficiency can be obtained.     

Power Transfer of a Parallel Optical Fiber Directional Coupler

This letter describes experimental results of a simple optical fiber directional coupler which picks up a small portion of the transmitted power in a main optical fiber transmission line without affecting the characteristics of the main line. This directional coupler consists of two fibers closely parallel in a certain coupling length; an index matching liquid, Si-oil, fills the coupling region. A 50-dB power coupling and 21=dB directivity are measured. Insertion loss is almost negligible. The measured power coupling is much larger than that expected by the simple coupling theory.     

A 5.8 GHz 1 V Linear Power Amplifier Using a Novel On-Chip Transformer Power Combiner in Standard 90 nm CMOS

A fully integrated 5.8 GHz Class AB linear power amplifier (PA) in a standard 90 nm CMOS process using thin oxide transistors utilizes a novel on-chip transformer power combining network. The transformer combines the power of four push-pull stages with low insertion loss over the bandwidth of interest and is compatible with standard CMOS process without any additional analog or RF enhancements. With a 1 V power supply, the PA achieves 24.3 dBm maximum output power at a peak drain efficiency of 27% and 20.5 dBm output power at the 1 dB compression point.     

A D‐Band Balanced Subharmonically‐Pumped Resistive Mixer Based on 100‐nm mHEMT Technology

A D‐band subharmonically‐pumped resistive mixer has been designed, processed, and experimentally tested. The circuit is based on a 180° power divider structure consisting of a Lange coupler followed by a λ/4 transmission line (at local oscillator (LO) frequency). This monolithic microwave integrated circuit (MMIC) has been realized in coplanar waveguide technology by using an InAlAs/InGaAs‐based metamorphic high electron mobility transistor process with 100‐nm gate length. The MMIC achieves a measured conversion loss between 12.5 dB and 16 dB in the radio frequency bandwidth from 120 GHz to 150 GHz with 4‐dBm LO drive and an intermediate frequency of 100 MHz. The input 1‐dB compression point and IIP3 were simulated to be 2 dBm and 13 dBm, respectively.     

A New Directional Coupler Design with High Directivity for PCS and IMT‐2000

This paper proposes a new design of directional couplers with high directivity for personal communication services (PCS) and International Mobile Telecommunications‐2000 (IMT‐2000). The directional coupler is used to check and verify the power, frequency, and antenna reflection of a signal at transmission stations for mobile communications. The performance requirements of directional couplers are a strong coupling to reduce the effect on the transmitted power and high directivity to suppress the interference of the reflected signals and reduce the errors in communication. So far, various architectures have been proposed to gain high directivity, and there have been many studies used to obtain a strong coupling. However, conventional architectures for high directivity and strong coupling have a directivity of only about 20 dB, and there have been difficulties to achieve the higher directivity of 30 dB suitable for PCS and IMT‐2000. This paper proposes a new architecture of directional couplers based on a grounding composed of strip lines, and compares the test results of this directional coupler with conventional ones. The results show that the proposed directional coupler has a directivity of more than 30 dB and is adequate for PCS and IMT‐2000.     

功率合成技术在全固态中波发射机的应用解析

首先阐述功率合成技术的概念、功率合成方法;其次,分析功率合成技术应用于全固态中波发射机中的必要性;最后,较为详细地探究λ/4传输线段功率合成、变压器混合网络以及3dB耦合器功率合成器用于全固态调频广播发射机中遵照的基本原理及应用要点。希望能和同行分享技术经验,在全固态调频广播发射机中更好的推广功率合成技术,将该项技术的优越性充分发挥出来。     

一种宽带高方向性微带定向耦合器

文中设计了一种小型化的具有高方向性的多节微带线定向耦合器。通过将耦合微带线分段处理,得到由一节1/4波长段和两节1/8波长段组合的多段耦合器。非均匀介质微带耦合线中奇偶模相速度的差异导致微带定向耦合器的方向性较差。文中通过在耦合器馈线拐角处采用1/4圆弧提高了方向性。通过优化仿真设计实现了10 GHz耦合器,耦合度为25 dB,并且从6~14 GHz的方向性优于30 dB。与传统的并联耦合线耦合器相比,文中所提出的耦合器具有更小尺寸和更加出色的方向性,且实测和模拟仿真基本一致。     

Design and Analysis of a 55–71-GHz Compact and Broadband Distributed Active Transformer Power Amplifier in 90-nm CMOS Process

A 55–71-GHz fully integrated power amplifier (PA) using a distributed active transformer (DAT) is implemented in 90-nm RF/MS CMOS technology. The DAT combiner, featuring efficient power combination and direct impedance transformation, is suitable for millimeter-wave (MMW) PA design. Systematic design procedures including an impedance allocation plan, a compensation line, and a gain boosting technique are presented for the MMW DAT PA. The monolithic microwave integrated circuit (MMIC) performs a high and flat small-signal gain of ${hbox{26}} pm {hbox{1.5}}~{hbox{dB}}$ from 55 to 71 GHz, which covers a full band for 60-GHz wireless personal area network applications. Using cascode devices and a DAT four-way power combination, the CMOS PA delivers 14.5- and 18-dBm saturated output power with 10.2% and 12.2% power-added efficiency under 1.8- and 3-V supply voltage, respectively, at 60 GHz. The maximum linear output power ( $ P _{1~{rm dB}} $) is 14.5 dBm. To the best of our knowledge, the MMIC is the first demonstration of a $V$-band CMOS PA using a DAT combining scheme with highest linear output power among the reported 60-GHz CMOS PAs to date.      

Linear 0.20 GHz modulation with a 1×2 directional coupler

The design and performance of a traveling-wave 1×2 directional coupler modulator are described. A 0-20 GHz response (-4 dB _e) was achieved for Ti:LiNbO₃ devices at the 1.3-μm wavelength. From experimental determinations of coupling coefficient and interarm intrinsic phase-mismatch for several modulators, linear dynamic ranges of, on average, 78 dB and voltage sensitivities of down to 9 μV are determined (for 1-mW detector power, 3-kHz bandwidth, 50-Ω detector load). The dependence of sensitivity on the coupling coefficient is described, and the effect of the buffer layer thickness on the optical bandwidth and sensitivity is demonstrated     

基于耦合三线结构的宽带功分器研究*

由于传统的威尔金森功分器需要通过多级传输线的级联来拓展其工作带宽,增加了电路设计的复杂度。因此本文提出了一种基于耦合三线的宽带功分器结构。通过在四分之一波长传输线的两端分别引入一节耦合三线,使功分器实现了宽带特性。采用三线耦合器与阻抗变换理论,对影响功分器工作带宽、输入输出端口匹配度和隔离度参数进行了理论分析,并设计制造了基于此结构的宽带功分器。测试结果表明该功分器具有很好的端口匹配、传输损耗和端口隔离特性。     

A new circuit topology for continuous group delay synthesis

A new circuit topology is realized in order to synthesize group delay continuously. The circuit is based upon a new variable coupling coefficient coupled line section and a microstrip feedback loop. The new variable coupler is designed by periodically loading an edge coupled microstrip coupler. With this new design, coupling variation of more than 10 dB may be achieved. To the best of the authors knowledge, this is the first report of this type of microstrip coupler. The complete circuit consumes no do power and exhibits more than 500 ps of continuous variable true time delay. Insertion loss is better than 3 dB and return loss is better than 15 dB     

Wide Dynamic Range Optical Power Control Based on Cascaded Fused Tapered Couplers for High-Power Yb-Doped Fiber Lasers

Wide dynamic-range optical power control was achieved in a novel all-fiber device for a high-power Yb-doped fiber laser input using a serially cascaded fused tapered coupler pair. Torsional stress was independently applied over the coupling zones, which resulted in phase changes by photoelastic effects and subsequent linear shifts in transmission spectra. Dynamic range of 46 dB and low insertion loss below 1 dB were achieved for 1060-nm fiber laser with the incident fiber coupled power of 3.4 W. The detailed fabrication process of the device, characterization, and theoretical background are discussed.      

Trenched‐Sinker LDMOSFET (TS‐LDMOS) Structure for 2 GHz Power Amplifiers

This paper proposes a new LDMOSFET structure with a trenched sinker for high‐power RF amplifiers. Using a low‐temperature, deep‐trench technology, we succeeded in drastically shrinking the sinker area to one‐third the size of the conventional diffusion‐type structure. The RF performance of the proposed device with a channel width of 5 mm showed a small signal gain of 16.5 dB and a maximum peak power of 32 dBm with a power‐added efficiency of 25% at 2 GHz. Furthermore, the trench sinker, which was applied to the guard ring to suppress coupling between inductors, showed an excellent blocking performance below ?40 dB at a frequency of up to 20 GHz. These results confirm that the proposed trenched sinker should be an effective technology both as a compact sinker for RF power devices and as a guard ring against coupling.     

30～150MHz宽带双定向耦合器设计

介绍了基于三线变压器魔T的双定向耦合器工作原理,分析了串联耦合信号与并联耦合信号通过魔T进行同相和反相合成的机理,应用电报方程分析它的阻抗变换特性,得到扭绞三线传输线变压器魔丁的最佳传输条件。设计了一种耦舍度为30dB的宽带双定向耦合器,并对其参数进行了理论分析和测量,满足设计要求,为充带双定向耦合器的设计和优化提供了理论基础。     

Tunable characteristics of ferrite composite right/left handed coplanar waveguide coupled line coupler – Measurement and experimental verification

This paper presents the experimental verification of the tunable characteristics of a ferrite composite right/left handed coupled line coupler. The coupler is designed using two coupled CRLH-CRLH transmission lines. The coupler is designed to demonstrate equal through and backward coupling. The novel coupler has been designed and realized in coplanar waveguide configuration on a ferrite substrate. The tunable characteristics are achieved by changing the applied DC magnetic bias to the ferrite substrate. The measurement results reveal that the coupler’s fractional bandwidth can be tuned from 29% to 69% by varying the applied DC magnetic bias from 1000 Oe to 1750 Oe. Within the tunable bandwidth, the maximum backward coupling is −5 dB. The coupler has high forward coupling isolation, close to −30 dB at its centre operating frequency. In addition to its tuning capability, the coupler has the advantages of its compact size; it has the length of 11.5 mm and not-so-tight line separations of 2.5 mm. Furthermore the coupler only requires low DC magnetic bias.     

A novel amplifying antenna array using patch-antenna couplers-design and measurement

This paper proposes a novel amplifying antenna array using the patch-antenna coupler formed by placing one or two open-ended microstrip lines (coupled lines) near and along the nonradiating edge(s) of a patch antenna. An X-band five-element array with broadside 25-dB Chebyshev radiation is demonstrated. When the input signal is fed to the center element, with most of the power radiating from the antenna, part of it is tapped to the coupled lines, amplified by an FET amplifier, and fed to the next antenna element. This process is repeated after all the antenna elements are fed with suitable power. The amplitude distribution of the fields radiated from the antennas is controlled by the coupling coefficient from the patch to the coupled line, which, in turn, is governed by the coupling length and gap between the patch and line. The measured return loss of the designed five-element array is -27 dB at the center frequency of 10 GHz with 2% 10-dB bandwidth. The radiation pattern possesses a transmitting gain of 15.9 dB, a half-power beamwidth of 17/spl deg/, and a sidelobe level of -22 dB.     

Study on Two‐Coil and Four‐Coil Wireless Power Transfer Systems Using Z‐Parameter Approach

A wireless power transfer (WPT) system is usually classified as being of either a two‐coil or four‐coil type. It is known that two‐coil WPT systems are suitable for short‐range transmissions, whereas four‐coil WPT systems are suitable for mid‐range transmissions. However, this paper reveals that the two aforementioned types of WPT system are alike in terms of their performance and characteristics, differing only when it comes to their matching‐network configurations. In this paper, we first find the optimum load and source conditions using Z‐parameters. Then, we estimate the maximum power transfer efficiency under the optimum load and source conditions, and we describe how to configure the matching networks pertaining to both types of WPT system for the given optimum load and source conditions. The two types of WPT system show the same performance with respect to the coupling coefficient and load impedance. Further, they also demonstrate an identical performance in the two cases considered in this paper, that is, a strong‐coupled case and a weak‐coupled case.     

Coupled-line metamaterial coupler having co-directional phase but contra-directional power flow

A coupled-line coupler comprising a microstrip line, edge-coupled to a negative-refractive-index line, exhibits co-directional phase but contra-directional Poynting vectors on the lines, leading to backward coupling. A key feature of this coupler is that it can support complex coupled modes. The resulting exponential field decay enables enhanced coupling with moderate line lengths and spacing. An example 3 dB device has been implemented and tested at 3 GHz.     

Coplanar-waveguide/microstrip probe coupler and applications to antennas

A method to couple microwave power from a coplanar waveguide to a microstrip line on opposite sides of a ground plane is demonstrated. The measured insertion loss and return loss are about 1 dB and 10 dB, respectively, across the frequency range of 0.045-6.5 GHz. To demonstrate potential applications of the coupler as a feeding network for a microstrip patch array measured radiation patterns for two rectangular patch antennas with a direct coplanar-waveguide/microstrip feed and with a proximity coupled coplanar-waveguide/microstrip feed are presented.<>     

A Novel Unequal Broadband Out‐of‐Phase Power Divider Using DSPSLs

In this paper, a novel unequal broadband out‐of‐phase power divider (PD) is presented. Double‐sided parallel‐strip lines (DSPSLs) are employed to achieve an out‐of‐phase response. Also, an asymmetric dual‐band matching structure with two external isolation resistors is utilized to obtain arbitrary unequal power division, in which the resistors are directly grounded for heat sinking. A through ground via (TGV), connecting the top and bottom sides of the DSPSLs, is used to short the isolation components. Additionally, this property can efficiently improve the broadband matching and isolation bandwidths. To investigate the proposed divider in detail, a set of design equations are derived based on the circuit theory and transmission line theory. The theoretical analysis shows that broadband responses can be obtained as proper frequency ratios are adopted. To verify the proposed concept, a sample divider with a power division of 2:1 is demonstrated. The measured results exhibit a broad bandwidth from 1.19 GHz to 2.19 GHz (59.2%) with a return loss better than 10 dB and port isolation of 18 dB.