Excellent Gain Flatness Research Articles

Packaging of an Amplifier Module for Sub-THz Wireless Transmission Based on Photonics

In this study, we have developed an amplifier waveguide module suitable for broadband communication in the sub-THz band. To achieve a waveguide module with excellent gain flatness characteristics, the effects of errors during the packaging procedures of the waveguide module and the space occupied by the bondwire were analyzed through an electromagnetic simulation. Furthermore, a photonics-based sub-THz wireless link with a carrier frequency of 288 GHz was established using a packaged amplifier module. The amplifier module was placed at the output of the sub-THz transmitter based on a uni-traveling-carrier photodiode and at the input of the sub-THz receiver. The maximum gain and 3 dB bandwidth of the amplifier module are 17.3 dB and 39 GHz, respectively. With this setup, we successfully transmitted a 100-Gbps 16-QAM modulated signal, employing a carrier frequency of 288 GHz, across a wireless distance of 100 m.

Analytical modelling of ultra‐small group delay variation of ultra‐broadband RF power amplifier using NSGA‐II algorithm

AbstractThis paper proposes a ± 9.4 ps ultra‐small group delay (GD) variation of fully integrated 65 nm complementary metal oxide semiconductor (CMOS) power amplifier (PA) over 6.5–17 GHz broadband for wireless application. The proposed CMOS PA is realised by using broadband stage, RLC inter‐stage and power stage topologies. The non‐dominated sorting genetic algorithm (NSGA‐II) is employed for PA parameter optimisation to ensure a small GD variation of ±9.4 ps over broadband with an excellent small signal gain flatness of 23.65 ± 1.85 for 6.5–17 GHz. The small GD variation of ±9.4 ps and ± 11.05 ps are attained under two cases of DC supply voltages of 2.4/1.2 V and 1.2/1.2 V, respectively. To the best of author's knowledge, the achieved GD variations are lowest among all CMOS PAs as reported so far. In addition, an analytical modelling of GD is derived to validating the minimum GD variation using zero‐pole compensation. With supply voltages of 2.4/1.2 V at 6.5 GHz, the large signal power gain, Psat and OP1dB are 26 dB, 19.3 dBm and 17.94 dBm, respectively, while peak power added efficiency (PAE) is 38.196%. At reduced supply voltages of 1.2/1.2 V, the PA achieves maximum power gain of 17.7 dB and peak PAE of 35% at 6.5 GHz. The CMOS PA occupies an area of 0.206 mm2.

An Ultra-Wideband Image-Reject Up-Conversion Mixer With a Sandwich-Coupled Transformer for 5G mm-Wave Communication

This letter presents an ultra-wideband 20–42 GHz image-reject up-conversion mixer with low dc-power consumption implemented in 55 nm CMOS technology for multiband mm-Wave 5G systems. A sandwich-coupled transformer (SCT) is adopted to expand the operation bandwidth. The proposed SCT demonstrates good performance in enhancing the coupling coefficient and quality factor, which enables wideband impedance matching. Moreover, a quadrature signal generator composed of a transformer and a polyphase filter (PPF) is utilized to generate wideband high-precision I/Q signals without any calibration. With only 24 mW dc-power consumption, the mixer exhibits excellent conversion gain flatness of 1.2±1.5 dB from 20 to 42 GHz. The measured image reject ratio (IRR) is better than −30 dBc within the entire operation band. The measured output 1-dB compression point (OP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1 dB</sub> ) is −2.57 dBm at 28 GHz and −3.96 dBm at 38 GHz. The proposed mixer exhibits good broadband characteristics, which can sustain multiband operation.

A Broadband Gain Amplifier Designed with the Models for Package and Diode Using 0.5 μm GaAs E-pHEMT Process

This paper presents a 50 MHz to 5 GHz broadband gain amplifier using a 0.5 μm gallium-arsenide pseudomorphic high-electron-mobility-transistor (GaAs pHEMT). For broadband design, a high gain cascode structure with a feedback network was used. To ensure the robustness of the design, the amplifier had to consider the effects of the Electrostatic Discharge (ESD)-protected diode and the package, which can degrade the broadband performance. Therefore, the equivalent circuit models of the package and the ESD-protected diode were analyzed and simulated in this paper. The designed broadband gain amplifier from 50 MHz to 5 GHz frequency band has a die size of 700 μm × 1000 μm and consumes 156 mW of dc power, and it was simulated with a gain of 18.7 dB to 20.6 dB, a P1dB of 15.3 to 16.9 dBm, and a OIP3 of 26.5 to 31 dBm. Furthermore, the excellent gain flatness exhibited within 18.7 dB ± 1.92 dB at the interest of the frequency band.

A Linearly Polarized Low-Profile Complementary Antenna With Enhanced Bandwidth and Wide Broadside Beamwidth

A linearly polarized low-profile complementary antenna with enhanced bandwidth and wide broadside beamwidth is proposed. To realize a wide half-power beamwidth (HPBW), an equivalent electric dipole is introduced by the strip on the bottom layer at first. As seen, it not only contributes to the beamwidth enlargement in yz-plane due to the superposition of complementary sources but also introduces a lower resonance. Then, in order to obtain a broad bandwidth, a stub is crossed on the strip to make the lower resonance move up, meanwhile merging with the higher one. After this, a tapered aperture structure is employed to reduce the input inductance for a further bandwidth enhancement. Finally, antenna prototype of center frequency 5 GHz is fabricated and tested. As experimentally demonstrated, a wide HPBW up to 180° and a broad bandwidth around 30% are achieved under a low-profile about 0.035λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> as well as excellent gain flatness property, which outperforms most of the reported counterparts.

Low‐power up‐conversion folded CMOS mixer for 2–12 GHz ultra‐wideband applications

This study presents an ultra-wideband up-conversion mixer chip that operates within the frequency range of 2–12 GHz using TSMC 0.18 μm complementary metal oxide semiconductor (CMOS) technology. The architecture is based on that of a Gilbert cell mixer. The design of the transconductance stage is based on an inverting amplifier. Two series resonant inductors are used to increase the conversion gain of the mixer, and a transformer that consists of two self-made inductors reduces the spatial requirement of the chip. This up-mixer achieves a 12.48 dB conversion gain and features an excellent gain flatness value of ±1.2 dB. The local oscillator (LO)-to-radio-frequency isolation is 44–20 dB, the input third-order intercept point (IIP3) is −6.8 to −8 dBm and the DC power consumption is 5.084 mW for a supply voltage of 1 V. The total size of the chip for the up-mixer is 1.2 × 1.2 mm2, including the pad frames.

Compact Planar Multipole Antenna for Scalable Wide Beamwidth and Bandwidth Characteristics

This article proposes a concept of compact planar multipole antenna configured by multiple magnetic and electric dipoles as a single radiation element with a single signal excitation port. The proposed structure uses diverse orientations in magnetic field and electric coupling through segmented radiation conductors and ground vias. The uniqueness of multipole antenna can be emphasized by its compactness, wide beamwidth in both the E- and H-planes with a finite ground plane size, and wide impedance bandwidth characteristics. To verify the concept of multipole structure, four different types of antennas are proposed and analyzed. With a radiation element size of $0.33\lambda _{\mathrm {o}}\,\, \times 0.33\lambda _{\mathrm {o}}$ ( $\lambda _{\mathrm {o}}$ for free-space wavelength) and a finite ground size of $1.1\lambda _{\mathrm {o}}\,\, \times 1.1\lambda _{\mathrm {o}}$ at 5.9 GHz, the half-power beamwidths (HPBWs) of 175° and 133° in both the E- and H-planes were measured, respectively. A wider bandwidth characteristic compared to previously reported wide beamwidth planar antennas was also achieved by one of the proposed structures. The measured 10 dB impedance bandwidth was about 13% with HPBWs of 111° and 160° in both the E- and H-planes, respectively. Also, the measured peak gains were better than 5.3 dBi for all structures with an excellent gain flatness at the operation band.

High Efficiency and Small Group Delay Variations 0.18-$\mu$ m CMOS UWB Power Amplifier

A new staggered tuning technique, by optimizing the inter-stage matching circuit, is proposed to realize a power amplifier (PA) with small group delay (GD) variations and excellent gain flatness across the full bandwidth of ultra-wideband (UWB) system. The proposed PA consists of two stages where the first stage is constructed by a current-reuse with shunt RC feedback topology to realize gain flatness and low power consumption. The design is implemented in 0.18 ${\mu }\text{m}$ commentary metal-oxide semiconductor (CMOS) technology, fabricated, and tested. The proposed PA has a measured power gain ( ${|{\mathrm{ S}}_{21}|}$ ) of 11.5 ± 0.7 dB, maximum power-added efficiency (PAE) of 26% and an output 1-dB compression point of 9 dBm, respectively, and this is the maximum PAE among CMOS PAs that cover the full bandwidth of UWB system. Besides, the PA has a small GD variations of ± 68 ps which is the lowest till date.

An 8–18 GHz power amplifier with novel gain fluctuation compensation technique in 65 nm CMOS * * Project supported partly by the National Natural Science Foundation of China (No. 60123456) and partly by the National 13th Five-Year Project.

A wideband CMOS power amplifier with high gain and excellent gain flatness for X–Ku-band radar phased array is proposed in this paper. Excellent gain flatness is achieved with transformer based matching networks (TMNs), in which the gain fluctuation of an inter-stage matching network can be compensated by the proposed design methods. The circuit is fabricated in the TSMC 65 nm RF CMOS process. The proposed technique is verified by the measurement results, which show that the wideband PA achieves gain of 21–22.5 dB with only ±0.75 dB gain fluctuation and 13–14.6 dBm flat output power between 7.5 and 15.5 GHz, and a little more ripple in the rest of the X–Ku band due to the inaccuracy of passive modelling at high frequency. The circuit delivers saturated and 1 dB-compressed output power of 14.6 and 11.3 dBm respectively at 13 GHz, for a maximal power-added efficiency (PAE) of 23%.

A low power 35 GHz CMOS high linearity, unconditional stability and excellent gain flatness UWB power amplifier design using current reused technique

A two-stage 0.18 µm RF CMOS current reused class-AB power amplifier design is proposed for 35 GHz ultra-wide-band application. It uses a cascade with current reused as first stage and common source with resistive feedback as a second stage. The simulation results shows a gain flatness of 24 dB and an input 1 dB compression of −14.63 dBm while consuming 22.6 mW of power from 1.8 V supply. Further, the input and output return loss of less than −9 dB and −15 dB respectively is obtained and reverse isolation of less than −58 dB provides good port to port isolation. The efficiency of the designed power amplifier is 24% at an input RF power of −5 dBm. Unconditional stability, good linear and low power consumption is the novelty of the proposed PA design with a considerable group delay of ± 550 pS.

Reconfigurable Modal Gain Control of a Few-Mode EDFA Supporting Six Spatial Modes

We experimentally demonstrate an inline few-mode erbium doped fiber amplifier supporting six spatial modes with reconfigurable differential gain control and excellent gain flatness obtained through mode-selective bidirectional pumping of a custom fiber with a radially profiled erbium dopant distribution. A signal gain of >20 dB was obtained for all the guided modes with a differential modal gain <;2 dB and good gain flatness across the C-band.

Variable gain-flattened L-band erbium-doped fiber amplifier

This is a study on the design of variable gain-flattened erbium-doped fiber amplifier operating in L-band transmission window. Four amplifiers divided into five stages became the basis of the design with distributed pumping configuration. A dispersion compensating module was incorporated into the architecture as a way to combat dispersion. The amplifier was able to generate variable gain from 15 up to 30 dB under different input signal powers with a maximum output power of 23 dBm. Excellent gain flatness averaging around 0.8 dB was accomplished while four-wave mixing effect was significantly reduced.

질화갈륨 소자를 이용한 DPD용 고집적 팔렛트형 고출력증폭기 모듈 설계

본 논문에서는 고출력 및 고효율 특성을 지니는 질화갈륨(gallium nitride, GaN) 고출력 트랜지스터 소자를 이용하여 WiMAX 및 LTE(long term evolution) 시스템에 사용 가능한 60watt급 고출력증폭기 모듈을 팔렛트(palette) 타입으로 개발한 결과에 대하여 기술한다. 높은 이득을 얻기 위한 라인업(lineup) 구성을 위해 저전력이면서 고이득을 지니는 전치증폭단, 8watt급의 GaN 구동증폭단, 그리고 30watt급 GaN 소자 2개를 도허티(doherty) 구조로 구성한 60watt 고출력증폭단을 사용하였으며, 이로부터 2.5~2.68GHz에서 61.4dB의 이득과 <TEX>${\pm}$</TEX>0.075dB의 우수한 이득 평탄도를 얻었다. 특히 구동단과 고출력증폭단은 고효율 및 고출력 특성의 GaN 소자를 사용하였고, 또한 추가적인 효율 개선을 위해 도허티 구조를 적용함으로써 보다 높은 효율을 가지도록 하였다. 현재 전 세계적으로 널리 사용되고 있는 WiMAX 신호를 사용하여 제작된 팔렛트 타입의 증폭기 모듈의 성능을 측정하였는데, RRH(remote radio head) 타입으로 구성된 사용 예에서 WiMAX 변조 신호 10watt 출력 기준으로 약 37~38%의 효율을 나타내었다. 제작된 증폭기 모듈을 디지털 전치왜곡기(digital predistorter, DPD)와 연동하여 시험한 결과 WiMAX 변조 신호 10watt 출력에서 ACLR은 46dBc 이상의 특성을 지닌다. This paper describes the design of a palette-type 60watt high power amplifier module using gallium nitride(GaN) devices with high power and efficiency performances for WiMAX and LTE systems. The line-up for the high gain amplifier module consists of the pre-amplifier stage with low power and high gain, 8watt GaN driving amplifier stage, and 60watt GaN high power amplifier stage of Doherty structure with two 30watt GaN devices. The obtained gain is 61.4dB with an excellent gain flatness of <TEX>${\pm}$</TEX>0.075dB over 2.5~2.68GHz. GaN devices and the Doherty structure are adopted for the improvement of high efficiency and output power. The measurement for the fabricated high power amplifier module of palette type is performed using the widely known WiMAX signal all over the world. In the example of RRH(remote radio head) application of the fabricated amplifier module, the measured efficiency is 37~38% with the 10watts of modulated output power. It is shown that when the fabricated amplifier module is activated with a digital predistorter(DPD), the measured ACLR is better than 46dBc under the 10watts of modulated output power.

Design of 1.2-V Broadband High Data-Rate MMW CMOS I/Q Modulator and Demodulator Using Modified Gilbert-Cell Mixer

In this paper, low-voltage evolution and high-speed operation mixer design are presented for millimeter-wave (MMW) CMOS in-phase/quadrature (I/Q) modulator and demodulator. The modified Gilbert-cell mixer architecture, which eliminates the three-level transistors stacking in the conventional Gilbert-cell mixer, can operate at a reduced supply voltage while maintaining reasonable performance. In addition, IF transimpedance amplifier buffer and wideband RF design are introduced to increase the operation speed of the mixer for MMW gigabit wireless transmission link applications. Using a 0.13-μm CMOS process, the I/Q modulator and demodulator formed with the modified Gilbert-cell mixers are demonstrated at the MMW. Under 1.2-V standard supply voltage, the modulator and demodulator exhibit excellent conversion gain (CG) flatness of -3.5 ±1.5 dB and -3 ±1.5 dB from 41 to 69.5 GHz and 31 to 69 GHz, respectively. For 60-GHz wireless personal area network applications, π/4 differential quadrature phase-shift keying, 16 quadrature amplitude modulation, and binary phase-shift keying modulation signal tests are successfully performed through the direct-conversion system. The results show that the presented monolithic microwave integrated circuits can operate at low-voltage and low-power while providing good CG and high data rate, even up to multigigabit.

An Excellent Gain Flatness 3.0–7.0 GHz CMOS PA for UWB Applications

This letter presents an excellent gain flatness CMOS power amplifier (PA) for UWB applications at 3.0-7.0 GHz in TSMC 0.18 μm CMOS technology. The UWB PA proposed here employs a current-reused technique to enhance the gain at the upper end of the desired band, a shunt and a series peaking inductors with a resistive feedback at the second stage to obtain the wider and flat gain, while shunt-shunt feedback helps to enhance the bandwidth and improve the output wideband matching. The measurement results indicated that the input return loss ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> ) less than -6 dB, output return loss ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sub> ) less than -7 dB, and excellent gain flatness approximately 14.5 ±0.5 dB over the frequency range of interest. The output 1 dB compression of 7 dBm, the output third-order intercept point (OIP3) of 18 dBm, and a phase linearity property (group delay) of ±178.5 ps across the whole band were obtained with a power consumption of 24 mW.

An Interconnecting Technology for RF MEMS Heterogeneous Chip Integration

An interconnecting technology using a Au-Au thermocompressive bond has been successfully developed for microelectromechanical system (MEMS) heterogeneous chip integration in this paper. The Daisy chain and RF transition structures are both designed and fabricated for the electrical characterization of the interconnect scheme. Measured dc contact resistance is about 14 ±5 m¿ for the bonding interface of Ni (1 ¿m)/Au (0.4 ¿m)/Au (0.4 ¿m)/Ni (1 ¿m) with a pad size of 40 ¿m in diameter. The electrical transition between two chips, which have coplanar waveguides (CPWs) and microstrip lines, respectively, can be well interconnected with less than - 15 dB return loss and - 1.8 dB insertion loss up to 50 GHz without implementing complex structure designs and extra impedance matching networks in the transition by employing this technology. Meanwhile, it is found that the mechanical strength for the interconnecting bond can be as large as 100 MPa. A low-power RF low-noise amplifier has been successfully designed, fabricated, and utilized in this paper to demonstrate the feasibility of the interconnecting technology for RF MEMS heterogeneous chip integration by integrating a Taiwan Semiconductor Manufacturing Corporation 0.18-¿m RF complimentary metal-oxide-semiconductor chip with a silicon carrier, where high <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> MEMS inductors are fabricated and utilized for good circuit performance in terms of excellent impedance matching, power gain, and gain flatness.

A 0.18 μm CMOS 3–5 GHz broadband flat gain low noise amplifier

A 3–5 GHz broadband flat gain differential low noise amplifier (LNA) is designed for the impulse radio ultra-wideband (IR-UWB) system. The gain-flatten technique is adopted in this UWB LNA. Serial and shunt peaking techniques are used to achieve broadband input matching and large gain-bandwidth product (GBW). Feedback networks are introduced to further extend the bandwidth and diminish the gain fluctuations. The prototype is fabricated in the SMIC 0.18 μm RF CMOS process. Measurement results show a 3-dB gain bandwidth of 2.4–5.5 GHz with a maximum power gain of 13.2 dB. The excellent gain flatness is achieved with ±0.45 dB gain fluctuations across 3–5 GHz and the minimum noise figure (NF) is 3.2 dB over 2.5–5 GHz. This circuit also shows an excellent input matching characteristic with the measured S11 below −13 dB over 2.9–5.4 GHz. The input-referred 1-dB compression point (IP1dB) is −11.7 dBm at 5 GHz. The differential circuit consumes 9.6 mA current from a supply of 1.8 V.

A Novel and Simple Maximum Available Gain Equalization Technique for Microwave Amplifiers

A novel method to equalize the maximum available gain (MAG) is presented. The method is based on the in- troduction of a simple interstage network between two transistors, where the set is treated as a single element. The tech- nique provides not only excellent gain flatness but also two additional advantages relative to conventional designs: sim- pler matching networks and smaller size. The method is simple, and the design is easy. A high gain L-band amplifier pro- totype has been developed to verify the equalization technique, achieving a few hundredths of dB gain flatness variation over the operation bandwidth.

A 60 GHz Medium Power Amplifier for Radio-over-Fiber System

We present the design and fabrication of a 60 GHz medium power amplifier monolithic microwave integrated circuit with excellent gain-flatness for a 60 GHz radio-over-fiber system. The circuit has a 4-stage structure using microstrip coupled lines instead of metal-insulator-metal capacitors for unconditional stability of the amplifier and yield enhancement. The gains of each stage of the amplifier are modified to provide broadband characteristics of input/output matching for the first and fourth stages and to achieve higher gains for the second and third stages to improve the gain- flatness of the amplifier for wideband.

Computational and experimental study of a microwave electromagnetic bandgap structure with waveguiding defect for potential use as a bandpass wireless interconnect

As clock rates continue to rise, problems with signal integrity, cross-coupling, and radiation may render impractical the baseband metallic interconnects presently used in computers. A potential means to address this problem is to use bandpass wireless interconnects operating at millimeter-wave center frequencies. We have conducted experimental and finite-difference time-domain (FDTD) computational studies scaled to a 10 GHz center frequency of single-row and double-row waveguiding defects within an electromagnetic bandgap structure. Our initial experimental results scaled to 10 GHz have verified the feasibility of achieving an approximately 80% bandwidth with excellent stopband, gain flatness, and matching characteristics. When scaled to millimeter-wave center frequencies above 300 GHz, this technology appears feasible of supporting data rates in the hundreds of Gb/s.