Wideband class-E Research Articles

A Systematic Approach of Generalized Reactance Compensation Technique in Wideband Class-E Power Amplifier for Lower High Frequency (HF) Bands

A Systematic Approach of Generalized Reactance Compensation Technique in Wideband Class-E Power Amplifier for Lower High Frequency (HF) Bands

Resonance gate bias cascode class-E power amplifier in GaAs pHEMT technology

In this paper, switching behavioural of cascode transistor in class-E cascode structure is improved by resonance gate bias (RGB) technique. The proposed technique can be used to increase supply voltage of a cascode class-E power amplifier (PAs) in order to achieve high output power and efficiency. Output power of class-E PAs are limited due to drain–gate stress caused by the switching transient voltages. The RGB technique relaxes the supply voltage limitation due to breakdown voltage (VBD) of the transistor. In addition, reactance compensation components technique is employed to achieve high-power and wide-band class-E PA. To show validity of the proposed RGB technique, two reliable 1-W high-voltage and high-efficiency class-E PAs are fabricated in a 0.25 μm GaAs pseudomorphic high-electron mobility transistor technology. The 1.8 GHz class-E PA achieves 52% power added efficiency (PAE) and 30.6 dBm output power. The designed 2–3 GHz class-E PA has 45% PAE at output power of 30 dBm.

Wireless Energy Transmission System for Implantable Device

A wireless energy transmission system based on magnetic coupling resonance was put forward for implantable device. Combining the calculation of self-inductance and mutual inductance between the transmitting and receiving spiral coil, the paper used circuit theory to model and simulate the characteristic of transmission system, the coil parameters including radius and number of turns can be determined accurately. The wideband Class-E power amplifier was used to drive the transmitting coil, its structure and working state were described in detail. Finally this paper carried on the experimental analysis to verify the theoretical derivation and system characteristics.

Wideband Digital Power Amplifiers With Efficiency Improvement Using 40-nm LP CMOS Technology

In this paper, two fully integrated digital power amplifiers (DPAs) intended for polar transmitters are proposed using a 40-nm CMOS technology, which achieve ultra wideband and high efficiency simultaneously. Firstly, the wideband Class-E power amplifier with nonideal characteristics is analyzed. Secondly, the design procedure of converting the nonideal Class-E model to a compact matching network is introduced for the on-chip implementation. Thirdly, the stacked-stepped-impedance transformer is utilized for the wideband output-matching network to improve the DPA power efficiency while tracking optimum load impedance. Finally, to enhance the saturated and back-off efficiency within a wideband, a novel feed-forward DPA architecture for a digital polar transmitter with multi-mode dynamic-matching (DM) network is firstly introduced and demonstrated. To verify the mechanism mentioned above, two DPAs are implemented and fabricated, which are the only reported wideband DPAs operating above 3 GHz with record fractional bandwidths, i.e., 92% and 100.8%, respectively. The proposed DPAs (i.e., DPA-I and DPA-II) exhibit peak output power of 22.2 and 22.3 dBm and peak drain efficiency of 46.2% and 47.4%, respectively, with a 1.2-V supply. In DM modes, the saturated and 6-dB back-off drain efficiency of DPA-II achieve maximum improvements of 7.5% and 5.7%, respectively. The core chip-sizes of the proposed DPAs (i.e., DPA-I and DPA-II) are 0.22 mm $^2$ and 0.24 mm $^2$ , respectively.

Improved Reactance-Compensation Technique for the Design of Wideband Suboptimum Class-E Power Amplifiers

A reactance-compensation technique has been introduced recently for the design of wideband class-E power amplifiers (PAs). With this technique, the load resistance can be transformed to an optimal complex drain impedance in a broad frequency band. One potential problem of this technique is that an additional network is often needed to transform 50 $\Omega$ to the optimum load resistance, which is typically at a lower value. This paper proposes a method to improve the reactance compensation technique. By using the proposed method, the required low-value load resistance is up to four times the original value. This is achieved not by adding more components, but by simply changing the order and values of them. With the proposed method, the additional resistance matching network is no longer needed in many cases, or can be significantly simplified in other cases. To validate the theory, two broadband class-E amplifiers were designed using the original technique and the proposed method, respectively. The performances of the two amplifiers are compared. By using similar complexity of matching networks, the PA designed using the original method can achieve better than 70% power-added efficiency for a fractional bandwidth of 42%. The PA designed using the proposed method can achieve above 70% efficiency for a bandwidth of 51%. The proposed method can be used in the design of many other types of amplifiers.

A full X-band CMOS amplifier with wideband class-E harmonic matching

A fully integrated medium power amplifier operating over the entire X-band is demonstrated in a 0.11-μm CMOS technology. A double-resonance technique is used for wideband input matching. At the output load, wideband class-E harmonic matching is performed for up to the third harmonic frequency to achieve high output power and efficiency. The amplifier exhibits measured small-signal gain exceeding 7.6 dB over a wide 3-dB bandwidth from 7.6 to 13.7 GHz. The output power and power added efficiency (PAE) are higher than 10.7 dBm and 15%, respectively, at the entire X-band (8–12 GHz). The peak PAE is 20.2% with an output power of 12.4 dBm at 10 GHz. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:645–649, 2015

Continuous Class-E Power Amplifier Modes

In this brief, a continuum of novel closed-form solutions is derived for class-E power amplifiers (PAs). It is analytically proven that the class-E zero voltage/zero voltage derivative switching conditions can be satisfied for an arbitrarily selected reactive second harmonic switch impedance (Z2S). The higher order harmonic currents are terminated capacitively. The conventional class-E, class- E/F2, and class-EF2 modes are thus subsets of the continuum. The arbitrary selection of Z2S enables robust waveform engineering for performance optimization in specific applications. Furthermore, the theoretical derivation provides important possibilities for wideband class-E PA synthesis.

Investigation of Wideband Load Transformation Networks for Class-E Switching-Mode Power Amplifiers

In this paper, single-ended and differential class-E load transformation networks (LTNs) for wideband operation are investigated. For this purpose, a differential third parallel-tuned tank LTN and a parallel-circuit load LTN without suppressing tanks are proposed to fulfill the class-E wideband condition. The differential parallel-circuit load (DPCL), which considers the finite RF chokes, has higher output resistance, and because of the differential structure, which ensures an open circuit at even harmonic frequencies, it is able to cover a wide frequency range. Consequently, the DPCL is well suited for highly integrated monolithic designs, as well as wideband application. Based on this analysis, a wideband class-E switching-mode power amplifier in CMOS 90 nm using the DPCL is designed. By deliberately combining the LTN with an on-chip balun, a compact size of 1.2 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is achieved. The circuit performance dependency on bond-wire length variation is analyzed and discussed. Measured results show a peak output power of 28.7 dBm, power-added efficiency (PAE) of 48.0%, and drain efficiency of 55.0% at 2.3 GHz. From 1.7 to 2.7 GHz, PAE is higher than 42% and output power is above 25 dBm.

High Power Wideband Class-E Power Amplifier

This letter shows a high-power, high-efficiency, wideband Class-E RF power amplifier designed upon the load admittance synthesis concept and built using an uncomplicated low-loss load network with a low loss wideband admittance transformer as the main component. It uses a power Silicon LDMOS transistor to provide up to 145 W at 28 V peak power, up to 86% drain efficiency over 35% fractional bandwidth (from 85 to 120 MHz) and 15.6 dB gain at peak power without any adjustments. These are clear performance advantages over previous published works and commercially available amplifiers at a similar frequency band and power level. The amplifier applications include FM broadcast, aeronautical communications, nuclear, MRI, heating or RF power stage for Envelope Elimination and Restoration transmitters.

Load–Pull Wideband Class-E Amplifier

A new technique to design wideband Class-E power amplifiers (PAs) based on the synthesis of specific load admittances at fundamental and harmonics is shown. This technique symplifies the design of wideband Class-E amplifiers by making it independent on any specific load network, implementation, and intrinsic transistor output capacitance COUT. Simulations and actual measurements on a 15-W VHF wideband Class-E PA prototype designed using this method show 35% fractional bandwidth with 80% drain efficiency