Envelope tracking (ET) linearizability of a power amplifier (PA) is studied in this paper. ET linearization can be explained as the cancellation between two intermodulation distortion (IMD) components [1,2]. The phase difference θ 0 between the two IMD components is identified as the criterion of ET linearizability. The IMD improvement by incorporating ET module with PA can be analytically calculated in terms of θ 0 . Excellent agreement between the prediction and measurement is achieved. Determination of θ 0 using three-tone measurement is proposed and demonstrated. ET linearizability is an inherent feature of a standalone PA itself, and can be quantitatively predicted before incorporating an ET module.

Envelope tracking (ET) linearization can be explained as the cancellation between two kinds of intermodulation distortions (IMD) [1]. A novel shaping function for ET linearization can thus be constructed by balancing the two IMDs. A dynamic approach of shaping function extraction, called slope tuning, is proposed and demonstrated in this study. Significant linearity improvements in a heterojunction bipolar transistor (HBT) power amplifier are experimentally achieved with extracted shaping function for both two-tone and long-term evolution (LTE) signals.

Additional intermodulation distortions (IMD) are generated in an envelope tracking (ET) power amplifier (PA) due to the mixing between RF input and ET signals. ET linearization can thus be achieved by the IMD cancellation. Analytical expressions depicting the ET linearization mechanism are derived. IMD cancellation is demonstrated with a three tone harmonic balance simulation. Significant linearity improvement is experimentally observed with both two-tone and modulated signals.

A wideband design method for a twisted eight-shape transformer is introduced with the design guidelines. The supply modulation effect caused by the fluctuation of virtual ground is analyzed. To minimize the effect, the different matching capacitors are adopted at each port and an accurate virtual ground is positioned. For verification, a fully integrated linear CMOS power amplifier (PA) is implemented in a 0.18-μm standard 1P6M RF CMOS process for 2.3- and 2.6-GHz m-WiMAX (IEEE 802.16e standard) system. In continuous-wave measurements, the two-stage Class-AB PA delivers 30.8-dBm saturated power with a 30.6% power-added efficiency (PAE) and 22-dB gain across 900-MHz bandwidth (defined as 1-dB gain bandwidth). In 16 quadrature amplitude modulation m-WiMAX modulation signal measurements, the PA generates 26.2-dBm average power with a 20.5% PAE. The PA complies with the spectrum mask at a 21-dBm average power level and satisfies 3% error vector magnitude at 17-dBm average power.

A transformer-based CMOS power amplifier (PA) is linearized using an analog predistortion technique for a 2.5-GHz m-WiMAX transmitter. The third harmonic of the power stage and driver stage can be cancelled out in a specific power region. The two-stage PA fabricated in a standard 0.18-μm CMOS process delivers 27.5 dBm with 27% PAE at the 1-dB compression point (P1dB) and offers 21 dB gain. The PA achieves 5.5 % EVM and meets the spectrum mask at 20.5 dBm average power. Another conventional PA with a zero-cross-point of gm3 bias is also fabricated and compared to prove its good linearity and efficiency.

In this work, a fully-integrated linear CMOS power amplifier (PA) is implemented in a 0.18-μm 1P6M RF CMOS process for 2.3-GHz and 2.6-GHz m-WiMAX system application. A wideband twisted figure-8-shaped transformer is utilized as both the power combining and matching, which is operated across 1 GHz bandwidth. The PA operates at Class AB mode and can deliver 29.1 dBm with a 26.5% PAE at 1-dB compression point and offer 22 dB gain. EVM is lower than 5% at 19 dBm average power under the 16 QAM m-WiMAX modulation signal test. Digital feedback pre-distortion (DFDPD) technique is employed to improve spectrum linearity by 7 dB at 19 dBm average power level.

A wideband envelope tracking power amplifier, which is robust to battery depletion, is introduced. An integrated boost converter keeps a stable operation of the PA supply modulator. Even at the battery depletion from 4.2 V to 2.8 V, there is no significant degradation of output power and linearity in the power amplifier. Moreover, the efficiency degradation by the additional regulator is minimized for the novel supply modulator architecture proposed in this work. The fabricated 2.535 GHz envelope tracking power amplifier presents max/min power-added efficiencies of 32.3/26.2% for 10 MHz BW 3 GPP LTE standard along the battery voltage from 4.2 V to 2.8 V.

A novel broadband transformer‐based CMOS power amplifier (PA) design method is studied in this article. To obtain a broadband PA, the parasitic parameters of the transformer are absorbed into the PAs load match and their impacts on bandwidth are studied. The fully‐integrated PA combined with an 8‐shaped transformer is implemented in 0.13 μm CMOS process with only 1.2 × 1.2 mm2 chip size and operates at Class AB mode. The single‐stage PA delivers 27.36 dBm output power with 27% efficiency and has 10.5 dB gain. It has 500 MHz bandwidth (1 dB degeneration) in the large and small signal measurements. IMD3 and IMD5 are also lower than −25 dBc at 19 dBm across the bandwidth. The spectrum of PA can meet the m‐WiMAX spectrum mask at 19 dBm average power level. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:422–425, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25731

This paper presents an efficient farfield simulation, exploiting and linking the strength of three commercial simulation tools. For many practical array and multiport antenna designs it is essential to examine the farfield for a general port excitation or termination scenario. Some examples are phased array designs, problems related to mutual coupling and scan blindness, tuning of parasitic elements, MIMO antennas and correlation. The proposed method fully characterizes the nearfield and the farfield of the antenna, so to compute farfield patterns by means of superposition for any voltage/current state at the port terminals. A recently published low-cost patch antenna phased array with analog beam steering by another group was found very suitable to demonstrate the proposed method.

The input power drive of Doherty power amplifier (PA) is analyzed and a proper input dividing technique without a coupler is introduced. The efficiency and linearity are enhanced by the uneven power drive and proposed output matching circuits. The PA circuit is realized using a 2-/mu m InGaP/GaAs HBT process and combined using merged lumped-components for Doherty operation. For wireless broadband (WiBro) application, which has 9.54 dB crest factor and 8.75 MHz bandwidth, the PA has EVM of 3% and PAE of 40.2% at an output power of 26 dBm. This data represents that the PA has an excellent efficiency and linearity performance for handset applications, while eliminating the burden of a coupler.

As a wireless handset deals with multiple application standards concurrently, RE transmitters and power amplifiers are required to be more power efficient and reconfigurable. In this paper, we review the recent advances in the design of the power amplifiers and transmitters. Then, the systematic design approaches to improve the performance with the digital baseband signal processing are introduced for the next generation mobile handset.

A polar transmitter supporting multi-standard applications through 0.13um CMOS hysteretic-controlled hybrid switching amplifier is presented with 1.88GHz HBT class-F PA operating with novel envelope shaping method for high efficiency and linearity over broad output power range. It achieves the PAE of 45/46/34.3% at the average output power of 27.8/29/23.9dBm for EDGE/WCDMA/Mobile-WiMax, respectively, while satisfying the linearity specification without any digital pre-distortion technique. There are about 7% and 3% improvements of the overall PAE for EDGE and WCDMA, respectively, through the adaptive multi-mode operation.

文章对微带线馈电结构的Vivaldi超宽带天线进行了设计,并对设计的Vivaldi天线进行了计算辅助优化设计,同时制作了试验样机.仿真测试结果表明,该天线在规定的3.1GHz-10.6GHz频段内可以得到良好的传输性能和辐射性能,与理论设计吻合,达到宽频带特性的设计要求,为Vivaldi宽带天线的设计提供了新的思路.

The class-AB/F power amplifier (PA), a multimode PA, which can operate at both class-AB and class-F modes, is analyzed and compared with the conventional class-F and class-AB PAs. The open-circuited third harmonic control circuit enhances the efficiency of the PA without deteriorating the linearity of class-AB mode of the PA. The voltage and current waveforms are simulated to evaluate the appropriate operation for the modes. To demonstrate the multimode PA, the PA is implemented using an InGaP/GaAs HBT process and it is tested with reverse-link IS-95A code division multiple access (CDMA) and PCS1900 global system for mobile communications signals in the personal communications service band. The class-AB operation for a CDMA signal delivers a power-added efficiency (PAE) of 38.9% and an adjacent channel power ratio of 49.5 and 56.5 dBc at the offset of 1.25 and 2.25 MHz, respectively, at the output power of 28 dBm. The maximum PAE of 64.7% under the class-F operation is measured at 32.5-dBm output power for a GSM signal. The class-AB/F PA is a good candidate for the multimode PA of next-generation wireless communication systems.

文章对微带线馈电结构的Vivaldi超宽带天线进行了设计,并对设计的Vivaldi天线进行了计算辅助优化设计,同时制作了试验样机。仿真测试结果表明,该天线在规定的3.1GHz～10.6GHz频段内可以得到良好的传输性能和辐射性能,与理论设计吻合,达到宽频带特性的设计要求,为Vivaldi超宽带天线的设计提供了新的思路。

This paper describes a methodology for developing an effective electromagnetic compatibility (EMC) computer based technical support platform (TSP) system which is used for the analysis, prediction and design of system-level EMC. This computer-based TSP is integrated by EMC resource databases, specifications modules EMC design module, platform management module and EMC analysis tools. The main advantage of such a system over conventional EMC software is that the platform is based on brower/server structure, which is developed by JAVA language so that it can be used for EMC engineers to operate on a personal computer in the local area network operated at conventional WINDOWS system environment. In addition, the platform does not require the users to be a skillful expert in system-level EMC design but it is easy for the users to complete EMC design based on the operation guide procedures. This platform has been used in the IT production for system-level EMC designers.

We propose a dual band CMOS power amplifier for mobile WiMAX systems. The power amplifier, combined with an active matching transformer, is fully integrated and fabricated in a 0.13μm CMOS process. The transformer operates at dual bands with active matching circuit. The measured result shows that the transformer efficiency of 78. 2% and 70. 4% at 2.5 and 3.5GHz are realized,respectively,and 26. 5 and 24.8dB gain are achieved. The PAE reaches 20% and 28% at 2. 5 and 3.5GHz,respectively. The third inter-modulation (IM3) is lower than-30dBc at the 25dBm average power.

This paper analyzes the bandwidth characteristic of a transformer with a view point of the impedance matching and provides design rules. Based on the rules, two designs were demonstrated, the dual narrow path band transformer and the distributed active transformer (DAT) optimized for a wide bandwidth.

A semi-lumped output transformer for fully-integrated RF CMOS power amplifier is proposed in this paper. We analyze and design the transformer with the even mode and odd mode method. To demonstrate this transformer, a 2.5 GHz CMOS power amplifier is implemented with 0.18 mum and 2.5/3.5 GHz dual band 0.13 mum RF CMOS process used for WiMax application are fabricated. The power amplifier can achieve 39% PAE (power added efficiency) at P1dB (1 dB compression point) output power of 30 dBm. The linearity can satisfy the spectrum mask of WiMax signal requirement basically for 2.5 GHz CMOS power amplifier. And the gain and PAE for dual band power amplifier can also achieve 26.5 dB and 24.8 dB and 24.5% and 27.5%, respectively.

A semilumped output transformer for fully-integrated RF CMOS power amplifier is proposed in this paper. To demonstrate this transformer, a 2.5-GHz CMOS power amplifier is implemented with a 0.18-mu m RF CMOS process used for WiMAX application. The power amplifier can achieve 39% PAE (power added efficiency) at P 1dB (1 dB compression point) and output power of 30 dBm. The linearity can satisfy the spectrum mask of the WiMAX signal requirement basically. (c) 2008 Wiley Periodicals, Inc.