X-band Power Amplifier Research Articles

Coplanar Asymmetry Transformer Distributed Modeling for X-Band Drive Power Amplifier Design on GaN Process

In this paper, a methodology for designing a distributed model for coplanar asymmetry transformer on gallium nitride (GaN) process is proposed, which can accurately characterize the transformer’s feature up to a millimeter-wave band. The paper analyses a transformer-based matching circuit and proposes a practical transformer design procedure. A two stage, transformer matching based X-band power amplifier (PA) is reported here. Using the proposed transformer model and correlated transformer design procedure can sharply reduce schematic design period and optimum process time. The PA chip is designed on a 0.25 µm GaN technology process and occupies a 1.515 mm2 area. At a 28 V supply, the gain and output power of the PA reaches 15 dB and 29 dBm respectively, and the wideband matching transformer reaches 47.6% bandwidth. To the best of our knowledge, the distributed model for coplanar asymmetry transformer and transformer-based X-band MMIC PA on GaN process in this work is the first case among the reported papers.

Design and Fabrication of a High-Efficiency and High-Gain X-Band Power Amplifier Using GaN-HEMT Die Transistors for Satellite Communications

Design and Fabrication of a High-Efficiency and High-Gain X-Band Power Amplifier Using GaN-HEMT Die Transistors for Satellite Communications

A Two-Stage X-Band 20.7-dBm Power Amplifier in 40-nm CMOS Technology

For higher integration density, X-band power amplifiers (PAs) with CMOS technology have been widely discussed in recent publications. However, with reduced power supply voltage and device size, it is a great challenge to design a compact PA with high output power and power-added efficiency (PAE). In the proposed design, a 40-nm standard CMOS process is used for higher integration with other RF building blocks, compared with other CMOS PA designs with larger process node. Transistor cells are designed with neutralization capacitors to increase stability and gain performance of the PA. As a trade-off among gain, output power, and PAE, the transistor cells in driving stage and power stage are biased for class A and class AB operation, respectively. Both transistor cells consist of two transistors working in differential mode. Furthermore, transformer-based matching networks (TMNs) are used to realize a two-stage X-band CMOS PA with compact size. The PA achieves an effective conductivity (EC) of 117.5, which is among the highest in recently reported X-band PAs in CMOS technology. The PA also attains a saturated output power (Psat) of 20.7 dBm, a peak PAE of 22.4%, and a gain of 25.6 dB at the center frequency of 10 GHz under a 1 V supply in 40-nm CMOS.

High linearity and high power performance with barrier layer of sandwich structure and Al0.05GaN back barrier for X-band application

The high power and linearity performance of GaN-based HEMT for X-band application was achieved using the barrier layer of sandwich structure and Al0.05GaN back barrier. The AlGaN-sandwich-barrier can modulate polarization-graded field for more flat transconductance profile under the high drain bias. Only about 7.5% current collapse (CC) occurs for drain quiescent bias of 40 V. Due to the Al0.05GaN back barrier, the three-terminal off-state breakdown voltage (BVDS) of 260 V and a very small drain-induced barrier lowering (DIBL) of 2.7 mV V−1 is achieved. The AlGaN sandwich barrier combined with Al0.05GaN back barrier device exhibits a high current-gain cutoff frequency f T of 42 GHz@VDS = 10 V, and a high power-gain cutoff frequency f MAX of 130 GHz@VDS = 60 V. Load-pull measurement at 10 GHz revealed a saturated power density of 7.3 W mm−1 was achieved with an associated PAE of 29.2% and Gain of 10.6 dB. Two-tone measurement at 10 GHz showed an OIP3 of 38 dBm and a corresponding linearity figure-of-merit OIP3/PDC of 4.5 dB. These results demonstrate the great potential of AlGaN-sandwich -barrier/GaN/Al0.05GaN HEMTs as a very promising alternative to high power and high linearity X-band power amplifier.

Realization of a broadband hybrid X-band power amplifier based on fT-doubler technique

This paper presents the design steps for the fabrication of a hybrid microwave power amplifier (PA) based on fT-doubler technique. The PA is implemented using two 6 W discrete GaN-HEMTs on SiC substrate. The fT-doubler technique is used to enhance the frequency response and bandwidth of the PA as compared to the common source (CS) configuration. Accurate simulation results show about 90% improvement in the unity current gain frequency (fT) for the fT-doubler structure in comparison with a common-source parallel structure. However, the hybrid realization of a high-frequency PA based on fT-doubler technique is challenging mainly due to severe thermal management failures and large parasitic effects of the interconnections such as bond wires and long microstrip lines. The proposed hybrid integrated strategy relieves the thermal problem while the parasitic effects are well controlled. Thermal analysis and accurate 3D thermal simulation of the proposed hybrid integrated structure show that the channel temperature of transistors does not exceed its maximum tolerable value. Implementing the optimal source/load pulls for the transistors and well-designing the input/output matching networks by considering the parasitic effects of the interconnections result in a fabricated PA with a broad bandwidth of 6.5–10.4 GHz, a sufficient small-signal gain of 10 dB, a considerably high output power (Pout) of around 10 W and a power added efficiency (PAE) of 43% at 8 GHz.

A 20.5-dBm <inline-formula> <tex-math notation="LaTeX">$X$ </tex-math> </inline-formula>-Band Power Amplifier With a 1.2-V Supply in 65-nm CMOS Technology

In this letter, we present an X-band power amplifier (PA) which achieves a saturated output power ( $P_{\mathrm {sat}}$ ) of 20.5 dBm under a 1.2-V supply in 65-nm CMOS. Considering the relatively low breakdown voltage of the 65-nm device, we adopted a differential configuration with a triple-well cascode in which the n-well of the cascode device was biased with a resistor. Also, the PA adopted an on-chip 1:2 transformer to provide a low output impedance at the drain, and a series RC feedback was employed to enhance the stability and the gain bandwidth (BW) as well. The measured 3-dB BW of the PA covered the whole X-band and supported an output 1-dB gain compression point (OP1dB) of 15.2 dBm. A peak power-added efficiency of 24.6% with a gain of 24.4 dB at 9 GHz was recorded. The core of the PA occupies only 0.48 mm2.

Development of X-Band Transceiver MMIC’s Using GaN Technology

This paper describes X-Band power amplifier (PA), low noise amplifier (LNA) and switches that can be used in transmit/receive modules which are developed with GaN technology. For Transmit chain two 25 W high power amplifiers that are tuned between 8-10 GHz and 10-12 GHz bands are designed. A low noise amplifier with 2 W survivability and less than 2dB noise figure is designed for receive chain Furthermore, an RF switch that is capable of withstanding 25 W RF power is developed for the selection of transmit or receive chains. Measurement results show that both power amplifiers produce 25 W of power. Low noise amplifier has more than 20 dB small signal gain with less than 2 dB noise figure. RF switch has 50 dB of isolation with less than 1 dB insertion loss.

A Highly Efficient X-Band Inverse Class-F SiGe HBT Cascode Power Amplifier With Harmonic-Tuned Wilkinson Power Combiner

A highly efficient sub-Watt X-band inverse class-F SiGe heterojunction bipolar transistor (HBT) cascode power amplifier (PA) is presented. With a multi-harmonic resonance filter and a low loss lumped-element Wilkinson power combiner as an output matching network, the inverse class-F operation is realized successfully and high output power and power added efficiency (PAE) are obtained simultaneously. A cascode configuration with a low base impedance termination and reduced voltage–current waveform overlap extends ${V} _{\rm{CE}}$ swing of the upper SiGe HBT in the cascode beyond BVCBO, leading to improvement in output power and PAE. As proof of concept, the proposed PA was implemented in a 0.13- ${{\mu }}\text{m}$ SiGe BiCMOS technology platform. Measured results shows 53.4% peak PAE with 26.1 dBm output power at 10 GHz, when operated on a 3.0-V supply. No performance degradation is observed after 24-h continuous mode operation. To the author’s best knowledge, this brief has the highest PAE among any Si-based X-band PAs with comparable output power, which demonstrates that the proposed harmonic-tuned Wilkinson power combiner approach is an appropriate solution for efficient PA design at X-band.

A Two-Stage <inline-formula> <tex-math notation="LaTeX">$S-/X$ </tex-math> </inline-formula>-Band CMOS Power Amplifier for High-Resolution Radar Transceivers

This paper presents a reconfigurable S-/X-band power amplifier (PA) integrated into a 0.18-μm RF CMOS process. A switchable transformer for output matching is operated by tuning its primary winding and a shunt capacitor under a 50-Ω load with passive efficiency of more than 63%/67% for the S-/X-band. Series resonant circuits with bond wires are employed at common-mode nodes, greatly improving the X-band performance of the PA. Despite the use of interstage matching without any tunable elements, the PA presents a power gain of more than 19.5 dB at both 3 and 8 GHz. The PA provides saturated output power of 24.8/21.5 (21.5) dBm with a power-added efficiency of 32.8%/11.1% (10.7%) at 3/8 (9) GHz. The 1-dB bandwidth is 0.6/2 GHz (2.8-3.4/7.5-9.5 GHz) for the S-/X-band. This amplifier demonstrates suitable performance for dual-band high-resolution radar transceivers.

X-band power amplifier for next generation networks based on mesfet

Advanced wireless standards of communication like 3GPP and LTE are becoming more and more efficient and with this evolution of communication systems mobile equipment is also become smaller and smaller. Power amplifier designing has become a very crucial task in this era where efficiency and size are the main concern of any designer. In this paper we have design and analyzed X-band Class E Metal-semiconductor field effect transistor (MESFET) based Power Amplifier. This device targets the devices which use OFDM technique to improve their spectral efficiency for the next generation communication systems. Microstrip lines are used to achieve small size for our design instead of lumped components. Load Pull measurements are used to get MESFET input and output impedances optimum values. For linear and non linear operation small signal mathematical model of the design is used. To reduce thermal losses FR4 substrate is used to increase PA efficiency. Our designs shows small values of input and output return loss of about -22.3dB and -23.716 dB achieving a high gain of about 25.6 dB respectively, with PAE of about 30 % having stability factor greater than 1 and 21.894dBm of output power

A Compact 60W X-Band GaN HEMT Power Amplifier MMIC

The design and performance of a compact X-band power amplifier MMIC utilizing Nanjing Electronic Devices Institute’s (NEDI’s) $0.25~\mu \text {m}$ gallium nitride (GaN) high electron mobility transistor (HEMT) technology is presented. The MMIC operates in pulse conditions with typical pulse width of $100~\mu $ sec and 10% duty cycle. An output power of 47.5 dBm to 48.7 dBm with over 20 dB power gain and a power added efficiency (PAE) of 40% to 45% over the band of 8-12 GHz under a drain voltage of 28 V have been achieved. The chip size is $3.5\times 3.8$ mm2 and the amplifier delivers an output power density up to 5.57 W/mm2 over the chip area and up to 6.43 W/mm over the active periphery of the power stage. The thermal resistance is 1.7 °C/W measured in CW mode.

An $X$ -Band Pulsed Load Modulation Transmitter With Multilevel Envelope Delta–Sigma Modulations

Switched mode RF power amplifiers (PAs) under bitstream modulations, such as bandpass or envelope delta-sigma modulations (EDSMs), have received increasing attentions over the past years. Such amplifiers offer high power efficiencies under power back-off conditions with pulse train voltage waveforms yet maintain their linearity in amplification through digital coding and modulations. This paper presented an X-band switched mode PA based on the pulsed load modulation (PLM) technique with multilevel EDSM to realize broadband efficient amplification of nonconstant-envelope signals. The complete theory of power efficiency for PLM under three-level EDSM is presented. The X-band PA is implemented with 0.25-μm discrete GaN transistors from Triquint. Both two-level and three-level EDSM techniques were tested and compared in regard to their quantization noise levels and power efficiencies. Under the three-level EDSM, the PA delivered 34.6-dBm output power for a WCDMA uplink signal with 100-MHz bandwidth and 5.3-dB peak-to-average power ratio at the carrier frequency of 9.2 GHz. The measured drain efficiency and the power-added efficiency with the modulation were 34.6% and 26.5%, respectively. The adjacent channel leakage power ratio at the output was measured to be 32.2/32.3 dBc at the 100-MHz offsets without using digital predistortion.

Load Modulation Measurements of X-Band Outphasing Power Amplifiers

This paper presents an in-depth investigation of both isolated and non-isolated outphasing power amplifiers, with and without supply modulation. X-band GaN MMIC power amplifiers with 70% power-added efficiency and 2.7 W output power at 10.1 GHz are configured in hybrid outphasing circuits with several combiners that include bi-directional couplers, enabling calibrated measurements of internal load modulation. It is experimentally demonstrated that the load modulation critically depends on the power balance of the two internal MMIC PAs. Despite the additional loss in the combiner, peak total efficiencies greater than 47% are achieved by full outphasing PAs with more than 3.7 W of output power. A comparison between several outphasing configurations quantifies the improvement in efficiency for both isolated and non-isolated outphasing PAs with supply modulation.

Waveform Evidence of Gate Harmonic Short Circuit Benefits for High Efficiency X-Band Power Amplifiers

An active load pull waveform measurement system has been utilized to investigate, by drain current waveform analysis, the effect of short circuits at the second and higher harmonics on the gate of a 750 μm Gallium Arsenide transistor. It is confirmed that the half wave rectified sinusoidal current waveform necessary for modes of operation such as class B, J and F is not optimally generated at X-Band frequencies for transistors controlled purely by bias. The disrupting effect of the nonlinear device gate capacitance must be accounted for to take full advantage of these high efficiency modes. The addition of a simple wide band filter circuit at the input of a MMIC test cell to “short” the gate higher harmonics is shown to force the drain current waveform towards the ideal case and hence yield a significant increase in drain efficiency of up to 10 percent.

X-Band CMOS Power Amplifier Using Mode-Locking Method For Sensor Applications

An X-band CMOS power amplifier using a mode-locking method for sensor applications is designed with a TSMC 0.13-μm RF CMOS process. The cascode structure is adapted to remove the reliability problems between the drain and gate voltages of the NMOS. Additionally, the mode-locking method is used to improve the efficiency and gain of the amplifier. We proposed the method to adapt the mode-locking topology to the cascode structure. The measured power added efficiency is 27%, while the saturated output power is 14 dBm at an operation frequency of 8.9 GHz. The designed chip size is 700 by 550 μm2.

Compact X-band SiGe power amplifier for single-chip phased array radar applications

An X-band power amplifier (PA) is presented for single-chip phased array radar applications. In this work, the choice of optimum circuit topology for X-band PA design is discussed and possible stability issues for high and low frequencies are analysed. The PA features a two-stage cascode architecture that includes both high-speed (low breakdown) and high breakdown (low-speed) SiGe transistors. It consists of two stages providing a 23.2 dBm saturated output power with a 28% power-added efficiency at 9 GHz. The output 1-dB compression point (P1dB) is higher than 20 dBm in a 3 GHz bandwidth and has a maximum value of 22.2 dBm. The small-signal gain is 25.5 dB with a 3-dB bandwidth of 3.2 GHz (7.3–10.5 GHz). The PA has been fabricated using 0.25 µm SiGe BiCMOS process provided by IHP Microelectronics. The PA occupies 1 mm×0.6 mm chip area and consumes 120 mA from a 4 V supply voltage. These results demonstrate comparable or better performance than other reported PAs and suitable performance for single-chip phased array applications.

An implementation of 60W X-band Cascade SSPA for Marine Radar System

In this paper, An X-band solid state power amplifier(SSPA) for pulse compressed microwave signal with 60Watt power and power added efficiency(PAE) above 30% is described. Designed 60Watt high power amplifier(HPA) was implemented by cascade coupled amplifiers, and it is consisted on three stage drive amplifiers with internally matched GaAs FET and one stage main power amplifier with an internally matched GaN HEMT. The designed SSPA has performance with more than total power gain 37dB and output power 48dBm(60-W) in condition of frequency range , pulse period width under 1ms and duty cycle under 10%. The implemented SSPA can apply to high quality digital marine radar applications with pulse compression technique.

Simple method for characterizing linear multi-port microstrip structures

A simple method for the full characterization of passive n-port microwave monolithic integrated circuit (MMIC) structures using standard two-port vector network analyzer (VNA) measurements is presented. Its main advantages are: it does not require to perform measurements from all the ports of the network, no special calibration procedure is needed, the auxiliary terminations required by the procedure can be integrated at the border of the structure under test with minimal area increase, and it can be easily implemented in commercial CAD software. The method was applied to a nine-port microstrip structure corresponding to the output power combiner and impedance matching network of an X-band MMIC high power amplifier (HPA). The full S-parameter matrix was derived from two-port measurements and compared to the circuit–as well as electromagnetic (EM)-based simulations of the structure.

고조파 제어 회로를 이용한 X-대역 전력 증폭기의 효율 개선에 관한 연구

본 논문에서는 간단하면서도 효과적인 능동적인 로드 풀(active load-pull) 방법을 제시하고, 고조파의 임피던스 성분을 제어하는 회로를 사용하여, X-대역 전력 증폭기의 효율을 개선시킬 수 있는 방법에 관하여 연구하였다. 제안된 능동적인 로드 풀 시스템은 크게 방향성 결합기와 위상 변위기, 단락 회로, 그리고 전력 증폭기로 구성되어 있으며, 전통적인 능동적인 로드 풀 방법에 비해 반사 계수가 1인 지점까지 임피던스를 쉽게 가져다 놓을 수 있다. 본 논문에서 사용된 소자는 Mitsubishi사의 GaAs FET인 MGF1801이며, 9 GHz의 동작 주파수에서 class-A일 때, 21.65 dBm의 출력 전력과 24.9 %의 드레인 효율을 얻었고, class-AB일 때, 21.46 dBm의 출력 전력과 53.3%의 드레인 효율을 얻었다. 고조파 제어 회로는 실험에 사용된 초고주파 부품의 주파수 대역폭의 한계로 인해, 2차와 3차 항 성분까지만 고려하여 설계하였으며, class-AB에서, 6.4 %의 효율이 증가된 것을 확인하였다. In this paper, a simple and effective active load-pull method is proposed, and the method to improve the efficiency of X-band power amplifier using harmonic control circuit is presented. The proposed active load-pull system mainly consists of directional coupler, phase shifter, short circuit, and power amplifier, and allows a user to access reflection coefficients near the edge of the Smith chart(<TEX>$\Gamma$</TEX>=1) easily. The device used in this paper is Mitsubishi's GaAs FET MGF1801, and the operating frequency of the power amplifier is 9 GHz, The amplifier had output power of 21.65 dBm and drain efficiency of 24.9 % at class-A, and had output power of 21.46 dBm and drain efficiency of 53.3 % at class-AB. Harmonic control circuit is designed only second and third harmonic components because of the bandwidth limitation of the microwave components. The drain efficiency is improved as much as 6.4 % compared with class-AB power amplifier.

An X-Band High-Power and High-PAE PHEMT MMIC Power Amplifier for Pulse and CW Operation

An X-band high-power and high power added efficiency (PAE), two-stage AlGaAs/InGaAs/GaAs psuedomorphic high electronic mobility transistor (PHEMT) monolithic microwave integrated circuit (MMIC) power amplifier is presented. The amplifier is designed to fully match a 50 Omega input and output impedance. Based on a 0.35 mum gate-length power PHEMT technology, the MMIC is fabricated on a 3 mil thick wafer. Under an 8 V DC bias condition, the characteristics of 17.5 dB small-signal gain, 10 W continuous wave mode saturation output power of 42% PAE, and 12.6 W pulse saturation output power of 52.6% PAE at 9.4 GHz can be achieved.