RF Power Amplifiers (original) (raw)

A New Topology of Load Network for Class F RF Power Amplifiers

High efficiency RF power amplifiers are increasingly needed in modern mobile communication systems to reduce the battery size and power supply consumption. Class-F RF power amplifiers offer improved efficiency over the conventional class-B power amplifiers by properly controlling the harmonic components of the voltage and current signals at the output terminals of the RF device while driving it to operate as an ON/OFF switch. To do this task, a suitable load network is to be synthesized in order to present the proper harmonic impedances at the output of the RF power transistor. In this paper, a new load network for class F power amplifiers has been introduced and derived analytically. The proposed network consists of a parallel short circuited λ/8 stub, parallel open circuited λ/8 stub, and a T-section lumped-element transformer. The benefits of this topology include simplicity of design, controllable bandwidth, and harmonic tuning and impedance transformation at the same time. To confirm the approach of analysis, a 10 W class-F UHF power amplifier circuit has been designed and simulated using a typical Gallium Nitride high electron mobility RF transistor (GaN HEMT) to operate at 500 MHz with the aid of the Advanced Design System (ADS) computer package. The simulated results have indicated that the circuit gives a dc-to-RF efficiency of more than 84 % and a power gain of 11 dB at 500 MHz with an operating bandwidth from 440 to 540 MHz. INTRODUCTION lass F RF power amplifiers are finding widespread applications in modern portable and base station transmitters due to their high-efficiency operation. The idealized operation of the class F RF power amplifier imposes the drain (or collector) voltage to be shaped as a square wave and the drain (or collector) current to be shaped as a half-wave sinusoidal waveform as shown in Figure (1) [1,2]. As seen from this sketch, there is no overlapping between the drain voltage and current waveforms, which means zero dissipated power in the RF transistor and thereby leading to 100% theoretical efficiency. If the RF device is assumed to operate as a switch then the shaping of the drain waveforms can be changed by controlling the harmonic components of the drain voltage and current through the insertion of multiple harmonic resonators in the output matching (or load) network of the power amplifier. These resonators must present open circuit (harmonic peaking) to the odd harmonic components and short circuit (harmonic termination) to the even harmonic components at the device output [3]. Accordingly, the drain to source voltage at the device output contains only odd harmonics while the drain current contains only even harmonics. In other words, the input impedance of the drain network represents an open circuit to the odd harmonics and a short circuit to the even harmonics.

An-Analysis-Of-Comparative-Class---E-Power-Amplifier.pdf

High power wideband amplifiers are demanded in many application areas, such as software defined radio, electronic warfare (EM), instrumentation systems, etc. The quality of the wireless communication system requires demand for compact, low-cost, and low power transportable transceivers has augmented dramatically. Among the transceiver’s building blocks is that the power electronic equipment. Thus, there's a desire for low-priced power electronic equipment. It’s necessary to think about the MOSFET gate-to-drain capacitance for achieving the class-E Zero Voltage Switching conditions. As a result, the ability output capability and therefore the power conversion potency are full of the MOSFET gate-to-drain capacitance. The waveform obtained from Analog to Digital simulations and circuit experiments showed the quantitative agreements with the theoretical predictions.

High Efficiency Classes of RF Amplifiers

2018

This article is dealing with high efficiency RF amplifiers in modern classes F, E and J. The first part is focused on basic function, main parameters and the output matching topologies of the mentioned classes. Output voltage and current waveforms were simulated for each class of high efficiency amplifiers. The primary focus of this work is the practical design of class F amplifier for 435 MHz band with E-pHEMT transistor. Power added efficiency (PAE) of amplifier achieved 58% and output power was 27 dBm with 14 dBm of input power. Amplifier was realized exclusively with lumped components in order to adhere to the given dimensions. Class F amplifiers designed at megahertz frequencies and with E-pHEMT transistor are quite rare and this article could help designers with understanding narrowband F-class amplifiers with higher efficiency. This amplifier can be used in long range IoT application, because of its low consumption of energy which is necessary in this modern technology. All r...

Systemizing the Design of Broadband Class-A RF Power Amplifiers

In the design of broadband microwave amplifiers, there are two techniques that are typically used to achieve gain-flatness across the frequency band of interest. The first technique is done through selective mismatch at lower frequencies of the band where the power gain is significantly higher. This can be achieved by degrading the VSWR at input or output at the low frequency band edge. The second technique is implemented by adding dissipative compensating networks. The input matching network is first designed to achieve minimum VSWR over the full band, and the required gain leveling is then done by adding the lossy equalizing circuit. This network is a constant resistance network and must have a roll-up insertion loss characteristic to compensate the inherent roll-off gain characteristic of the RF transistor over the entire frequency band. The second technique has been implemented to design a class-A linear power amplifier to operate within the frequency band from 225 MHz to 400 MHz and to deliver 20 dBm output power with more than 12 dB power gain over this communication band. The design strategy will be presented in a systematic manner in this article.

Analysis and design of class-O RF power amplifiers for wireless communication systems

Analog Integrated Circuits and Signal Processing, 2016

In this paper, we present analysis, design and show experimental results of a new type of CMOS based power amplifier (PA) known as class-O Aref et al. (ISSCC Digest of Technical Papers, 2015). Modern CMOS based PAs design is constrained by three fundamental trade-offs, i.e. linearity, efficiency and reliability. More precisely, for a standalone PA, unless advanced and expensive solutions are employed, no such PA architecture exists which is able to meet aforementioned design trade-offs. Theoretical insight is needed to understand the origin of performance trade-offs and the possible solutions to counter them. Class-O is a novel out-of-the-box solution to meet these tough challenges. Our prototype amplifier is a highly linear low-band 706 MHz 4G long term evolution (LTE) compatible class-O RF power amplifier in 130 nm CMOS technology for handheld wireless applications. The class-O architecture uses two sub-amplifiers working together as one grand PA. These two sub-amplifiers are commonsource (CS) and common-drain (CD) amplifiers working in parallel feeding a common load with high linearity without the need for digital predistortion (DPD). The prototype chip is measured and characterized with continuous wave (CW), modulated signal and reliability measurements. With CW measurements, 1-dB compression point (P 1 dB) of 30.6 dBm and peak power added efficiency (PAE) of 45.2 % is achieved. For the modulated signal measurements, the amplifier is tested with 16-QAM 20 MHz LTE signal with peak-to-average-power ratio of 6.54 dB. The amplifier meets the stringent LTE specs with an adjacent channel power ratio (ACPR) less than-30 dBc for both EUTRA and UTRA1 with average output power of 27 dBm and PAE above 20 %. Owing to the voltage following between gate source junctions in the common-drain amplifier in addition to cascode structure of common source amplifier, the stress is significantly reduced at the transistor terminals. The reliability is demonstrated by operating the amplifier in nominal and worst voltage-standing-wave-ratio (VSWR) conditions.

Design Method for UHF Class-E Power Amplifiers

2009 Annual IEEE Compound Semiconductor Integrated Circuit Symposium, 2009

This paper describes a method for designing singleended high-efficiency switched-mode class-E UHF power amplifiers. The design procedure consists of a modified load pull transistor characterization from which a power/efficiency metric is calculated. Results for four prototypes using different device technologies are presented in detail. Amplifiers with Si-LDMOS, SiC-MESFET, GaN-HEMT on a Si substrate, and GaN-HEMT on a SiC substrate produce power over 40W with power-added efficiency greater than 75% and gain between 13 dB and 17 dB.

A Methodology for Realizing High Efficiency Class-J in a Linear and Broadband PA

IEEE Transactions on Microwave Theory and Techniques, 2000

The design and implementation of a class-J mode RF power amplifier is described. The experimental results indicate the class-J mode's potential in achieving high efficiency across extensive bandwidth, while maintaining predistortable levels of linearity. A commercially available 10 W GaN (gallium nitride) high electron mobility transistor device was used in this investigation, together with a combination of high power waveform measurements, active harmonic load-pull and theoretical analysis of the class-J mode. Targeting a working bandwidth of 1.5-2.5 GHz an initial power amplifier (PA) design was based on basic class-J theory and computer-aided design simulation. This realized a 50% bandwidth with measured drain efficiency of 60%-70%. A second PA design iteration has realized near-rated output power of 39 dBm and improved efficiency beyond the original 2.5 GHz target, hence extending efficient PA operation across a bandwidth of 1.4-2.6 GHz, centered at 2 GHz. This second iteration made extensive use of active harmonic load-pull and waveform measurements, and incorporated a novel design methodology for achieving predistortable linearity. The class-J amplifier has been found to be more realizable than conventional class-AB modes, with a better compromise between power and efficiency tradeoffs over a substantial RF bandwidth.

Introduction to RF Power Amplifier Design and Simulation

Introduction to RF Power Amplifier Design and Simulation, 2015

Introduction to RF Power Amplifier Design and Simulation By Abdullah Eroglu Introduction to RF Power Amplifier Design and Simulation fills a gap in the existing literature by providing step-by-step guidance for the design of radio frequency (RF) power amplifiers, from analytical formulation to simulation, implementation, and measurement. Featuring numerous illustrations and examples of real-world engineering applications, this book: Gives an overview of intermodulation and elaborates on the difference between q linear and nonlinear amplifiers Describes the high-frequency model and transient characteristics of q metal-oxide-semiconductor field-effect transistors Details active device modeling techniques for transistors and parasitic q extraction methods for active devices Explores network and scattering parameters, resonators, matching networks, q and tools such as the Smith chart Covers power-sensing devices including four-port directional couplers and new q types of reflectometers Presents RF filter designs for power amplifiers as well as application examples q of special filter types Demonstrates the use of computer-aided design (CAD) tools, implementing q systematic design techniques Blending theory with practice, Introduction to RF Power Amplifier Design and Simulation supplies engineers, researchers, and RF/microwave engineering students with a valuable resource for the creation of efficient, better-performing, low-profile, high-power RF amplifiers.

Class-E Amplifier Design Improvements for GSM Frequencies

The Journal of Engineering Research [TJER], 2011

Efficient power amplifiers are essential in portable battery-operated systems such as mobile phones. Also, the power amplifier (PA) is the most power-consuming building block in the transmitter of a portable system. This paper investigates how the efficiency of the power amplifier (which is beneficial for multiple applications in communcation sector) can be improved by increasing the efficiency of switching mode class E power amplifiers for frequencies of 900 MHz and 1800 MHz. The paper tackles modeling, design improvements and verification through simulation for higher efficiencies. This is the continuation of previous work by the authors. These nonlinear power amplifiers can only amplify constant-envelope RF signals without introducing significant distortion. Mobile systems such as Advanced Mobile Phone System (AMPS) and Global System for Mobile communications (GSM) use modulation schemes which generate constant amplitude RF outputs in order to use efficient but nonlinear power a...

The class-E/F family of ZVS switching amplifiers

IEEE Transactions on Microwave Theory and Techniques, 2003

A new family of switching amplifiers, each member having some of the features of both class E and inverse F, is introduced. These class-E/F amplifiers have class-E features such as incorporation of the transistor parasitic capacitance into the circuit, exact truly switching time-domain solutions, and allowance for zero-voltage-switching operation. Additionally, some number of harmonics may be tuned in the fashion of inverse class F in order to achieve more desirable voltage and current waveforms for improved performance. Operational waveforms for several implementations are presented, and efficiency estimates are compared to class-E. Index Terms-Class E, class E/F, class F, harmonic tuning, high-efficiency amplifier, switching power amplifier, zero voltage switching (ZVS). I. INTRODUCTION F OR power-amplifier and power-inverter applications, harmonic-tuned switching amplifiers such as class E [1], [2] and class F [3] offer high efficiencies at high power densities. By operating the active device as a switch rather than a controlled current source, the voltage and current waveforms can, in principle, be made to have no overlap, reducing the theoretically achievable device dissipation to zero. At the same time, unlike in class-C operation, the output power of switching modes can be comparable to or greater than that of class A or class B for the same device peak voltage and current. For applications wherein AM/AM and AM/PM distortion can be tolerated [4], or compensated for [5], such amplifiers can improve efficiency and reduce heat-sink requirements. High-speed power converters, such as dc-dc converters, similarly benefit from improved RF power-amplifier efficiency [6]. Unfortunately, only two types of amplifier tunings appropriate for high-frequency operation, i.e., class E and class F, have been explored. Class-E amplifiers have found most application as a higher performance alternative to class-D amplifiers due to their compensation for transistor output capacitance and elimination of turn-on switching losses. Additionally, the class-E design may be implemented with a relatively simple circuit. These benefits have allowed class-E designs to push far beyond the frequencies achievable by class-D designs, with recent results reporting 55% at 1.8 GHz using CMOS devices [7] and