Envelope Tracked Pulse Gate Modulated GaN HEMT Power Amplifier for Wireless Transmitters (original) (raw)
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Development of a GaN HEMT class-AB power amplifier for an envelope tracking system at 2.45 GHz
2010
A class-AB power amplifier was designed for an envelope tracking (ET) application. Class-AB amplifier is widely used in wireless communication systems due to the compromise between linearity and efficiency. As a power device, Cree Gallium Nitride High Electron Mobility Transistor (GaN HEMT) CGH4010F was chosen. The input and output matching networks were designed and simulated with Advanced Design System (ADS). After some optimization, the amplifier was fabricated using a Rogers RT/Duroid 5880 substrate. The amplifier together with a MAX2247 preamplifier as a driver was measured. A good agreement between the simulation and measurement results was observed. The maximum power added efficiency (PAE) is around 50 percents with the supply voltage Vsup= 10V and the maximum drain efficiency is around 75 percents with Vsup= 5V. An output power up to 42 dBm and good linearity of the output voltage with respect to the supply voltage in the range 0≪Vsup≪20V were achieved. Thus, the amplifier i...
Design of a high efficiency GaN-HEMT RF power amplifier
2015
This paper presents the design and implementation of a GaN-HEMT, c1ass-J power amplifier suitable for cognitive radio transceivers, i. e., which presents high-efficiency and wideband characteristics, being these maintained for large load variations. Simulation results are presented which show large signal measurement results of 30 dB gain with 60%-76% power added efficiency (PAE) over a band of 1.3-2.3 GHz. Adaptivity to load changes is being developed to ensure PAE above 70% for large load variations.
A GaN HEMT power amplifier with variable gate bias for envelope and phase signals
Norchip 2007, 2007
This paper describes the design, simulation and measurement of a GaN power amplifier suitable for envelope and phase signal combination. The low-frequency envelope signal is used to vary the gate (bias) voltage of the device, resulting in a pulse width modulated drain voltage, while modulation of supply voltage or current is avoided. The test circuit is implemented using a discrete GaN HEMT power amplifier and discrete surface-mount passive components assembled on a PCB. Measurements showed a maximum drain efficiency of 59% at 360 MHz, at an output power of 29 dBm. The output power as a function of the gate bias voltage varied between 3 and 29 dBm, with the drain efficiency varying between 6 and 59%.
GaN HEMT power amplifier design for 2.45 GHz wireless applications
SAIEE Africa Research Journal
Electronic devices with high performances like Power Amplifiers (PA) are very important for Wireless communications. This paper proposes a design of a class AB power amplifier operating at 2.45 GHz, in the S-band frequency. The Cree's CG2H40045F GaN HEMT (High Electron Mobility Transistor) is used for this design. The Gallium Nitride (GaN) technology has been chosen in light of its advantageous properties such as high breakdown voltage, high band gap, as well as high thermal conditions. The paper investigates the different design trade-offs for finding a good balance between various key parameters of the PA (linearity, efficiency, and gain). A design approach has been proposed and the microstrip lines based on the Smith Chart tool available in ADS software have been used for the matching process. The class AB was selected to reach a good agreement between linearity and efficiency, provided by this class. After various process applications from DC characterization to simulations, the proposed design achieves a power added efficiency more than 50% at power saturation with a gain of 15 dB in schematic simulation. The layout dimensions are 55.5 x 64.45 mm 2 on PCB technology.
IEEE Transactions on Circuits and Systems I-regular Papers, 2015
We present a highly efficient RF transmitter over broad average power range using a multilevel envelope-tracking power amplifier (ML-ET PA). The ML-ET PA delivers enhanced efficiency at a back-off power region for handset applications. The supply modulator consists of a linear regulator and a switching converter. The DC supply of the linear regulator is adjusted according to the average power of the envelope signal, and the power-supply-independent class-AB output stage is employed to avoid the crossover distortion generated by the different DC supply voltages. The switch current level is not optimally adjusted by itself following the power back-off level, because the DC supply voltages of the linear regulator and switching converter are different. For the optimum operation over the entire power region, the switch current level is adjusted by detecting the input envelope voltage level. For a 20-MHz long term evolution signal with a 7.5 dB peak-to-average power ratio, the proposed supply modulator delivers a peak voltage of 4.5 V to a 6.5 load with a measured efficiency of 75.9%. The proposed ET PA delivers a power-added efficiency (PAE) of 40%, gain of 28.8 dB, evolved universal terrestrial radio access adjacent channel leakage ratio of 35.3 dBc, and error vector magnitude of 3.23% at an average output power of 27 dBm and an operating frequency of 1.71-GHz. At a 10 dB back-off point, the PAE is improved from 14.5% to 18.7% compared to the conventional ET PA.
High-Efficiency RF Pulsewidth Modulation of Class-E Power Amplifiers
IEEE Transactions on Microwave Theory and Techniques, 2011
A new switch mode power amplifier (SMPA) topology particularly suitable for energy efficient amplification of radio frequency pulse width modulation (RF-PWM) signals is derived. It is analytically shown that high efficiency can be maintained over a wide power dynamic range if the imaginary part of the Class-E load impedance is varied along with the duty cycle (pulse width). Using the theory developed, an explicit design procedure is presented that allows practical realization of the proposed topology from the circuit and component specifications. Following the design procedure, and using in-house (Chalmers University) SiC varactor diodes to implement the tunable imaginary load impedance, a 2 GHz 10 W peak output power GaN HEMT circuit demonstrator is realized. RF-PWM input signals for characterization of the prototype PA is generated with a dedicated 65 nm CMOS modulator. The measurements show that a drain efficiency > 70% can be obtained over an 6.5 dB dynamic range, which verifies the theory presented and demonstrates the feasibility of the proposed PA topology.
2024
This study presents a highly efficient Doherty Power Amplifier (DPA). The design uses 10W GaN High-Electron-Mobility Transistors (CG2H40010F) for their characteristics, such as high breakdown voltage and power density. Advanced Design Software (ADS) was used to conduct the design. The design configuration employed a pair of individual Power Amplifiers (PAs) and connected them via a Wilkinson Power divider (WPD), which also facilitates the transmission of power towards the charge. The Doherty Power Amplifier (DPA) has been designed to offer high efficiency, output power, and wide bandwidth, in addition to expanding power back-off levels. It operates within the 2.0-2.8 GHz frequency range. The DPA topology replaces the previous quarter-wave transformer with a Wilkinson Power Combiner (WPD). Simulation results show a fractional bandwidth of 33.33%, a saturated output power of 44 dBm, and a higher gain of approximately 15 dB. Furthermore, Drain efficiency (Deff) and Power-Added Efficiency (PAE) stand at approximately 85% and 95%, respectively. After linearization, the design produced an output power of 39.171 dBm using a 100 MHz, 6.5 dB PAPR 5G NR DL signal at 2.4 GHz. Additionally, it achieved an ACLR of-56.88 dB for the adjacent channel. The outcomes of this study indicate that the proposed DPA achieves excellent drain efficiency, providing a solution for increasing DPA bandwidth while maintaining linearity. The intrinsic features of GaN devices, which allow for higher frequency operation and wider bandwidth, make this design ideal for 5G applications.
IEEE Transactions on Microwave Theory and Techniques, 2019
Envelope tracking (ET) is a promising power amplifier (PA) architecture for current and future communications systems, that uses dynamic modulation of the supply voltage to provide high efficiency and potentially very wide bandwidth over a large dynamic range of output power. The dynamic nature of the supply voltage can lead to a problematic variation in transistor gain however, particularly in GaN HEMTs. This paper describes and analyses this behaviour and the detrimental effect it can have on ET PAs. Contributing factors and origins of gain variation are described in detail along with how, for the first time, meaningful comparisons can be made between different devices. Using these guidelines, gain variation is shown to be a widespread issue effecting most GaN HEMTs presented in literature. To allow an analysis of the intrinsic device behaviour, an extended transistor model is developed that takes the effect of gate and source field plates into account. This model is refined using measurement data and used to demonstrate the fact that the parasitic gate-drain capacitance (C GD) is the main contributor to the small-signal gain variation; a significant part of the overall gain variation. Based on this knowledge, possible strategies to reduce gain variation at the transistor technology level are proposed, allowing the optimisation of GaN HEMTs specifically for ET PAs. One identified strategy involves reducing the length of the gate field plate, and is shown to be a viable approach to reduce the gain variation in GaN HEMTs, albeit at an increased RF/dc dispersion.
2013
In this paper, implementation and testing of non- commercial GaN HEMT in a simple buck converter for envelope amplifier in ET and EER transmission techn iques has been done. Comparing to the prototypes with commercially available EPC1014 and 1015 GaN HEMTs, experimentally demonstrated power supply provided better thermal management and increased the switching frequency up to 25MHz. 64QAM signal with 1MHz of large signal bandw idth and 10.5dB of Peak to Average Power Ratio was gener ated, using the switching frequency of 20MHz. The obtaine defficiency was 38% including the driving circuit an d the total losses breakdown showed that switching power losses in the HEMT are the dominant ones. In addition to this, some basic physical modeling has been done, in order to provide an insight on the correlation between the electrical characteristics of the GaN HEMT and physical design parameters. This is the first step in the optimization of the HEMT design for this particular application.