Continuous Inverse Class-F Research Articles

Optimization design of fragment-type filtering matching network for continuous inverse class-F power amplifier

Optimization design of fragment-type filtering matching network for continuous inverse class-F power amplifier

A Broadband High-Efficiency Hybrid Continuous Inverse Power Amplifier Based on Extended Admittance Space

A novel hybrid continuous inverse power amplifier (PA) that is constituted by a continuum of PA modes from the continuous inverse class-F to the continuous inverse class-B/J is proposed, and a detailed mathematical analysis is presented. The fundamental and second harmonic admittance spaces of the hybrid PA proposed in this article are analyzed mathematically. By introducing the phase shift parameter into the current waveform formula of the hybrid continuous inverse PA, the design space of the fundamental and second harmonic admittance is expanded, further increasing the operating bandwidth. The efficiency of the amplifier under different parameter conditions is calculated. In order to verify this method, a broadband high-efficiency PA is designed and fabricated. The drain voltage and current waveforms of the amplifier are extracted for analysis. The experimental measured results show a 60.7–71.5% drain efficiency across the frequency band of 0.5–2.5 GHz (133% bandwidth), and the designed PA can obtain an 11.8–13.9 dB gain in the interesting frequency range. The measured results are confirmed to be in good agreement with theory and simulations.

Highly efficient Doherty power amplifier using continuous inverse class‐F and class‐J hybrid mode

A continuous inverse class-F (CCF−1) and class-J hybrid mode for the carrier power amplifier (PA) of the Doherty power amplifier (DPA) is proposed in this paper. In this hybrid mode, the carrier PA works in the CCF−1 mode at the saturated output power and the class-J mode at the low output power, which extends the design space of the conventional single continuous mode. A highly efficient Doherty power amplifier based on this hybrid mode is designed and fabricated using a CGH40010F 10 W GaN HEMT packaged device. The measurement results illustrate that drain efficiency (DE) of 67.2% to 81.7% at the saturated output power (Pout) and 50.4% to 60.1% at 6 dB output back-off (OBO) is achieved across the band 1.5 to 2.1 GHz with the saturated output power is about 43.3 to 44.6 dBm.

Design of a Self-Driving Transistor-Based RF-DC Converter Based on Optimized Harmonic-Tuned Rectification Waveforms

In order to apply the traditional power amplifier’s (PA) waveform engineering in an RF-dc rectifier design, a piecewise ON-resistance transistor model is introduced into the derived equations. In this proposed analysis method, the connection between the drain voltage and current is built in order to make the theoretical waveforms easily applied to a practical rectifier design with optimized parameters of the best efficiency. Continuous class-F/inverse class-F and continuous class-B/J waveforms are evaluated with numerical examples in this work. Thus, the rectification performance with different classes and parameters can be compared. This study shows that a continuous class-F and a continuous class-B/J rectifier can barely offer higher than 52% and 70% efficiencies with precise on-duty ratio ( $D$ ) of 0.5, respectively, except by reducing the conduction angle. However, a continuous inverse class-F shows the best rectification efficiency (easily higher than 85%) among all the studied cases for $D=0.5$ . A self-driving inverse class-F design example with optimized parameters is given to verify the theoretical analysis and demonstrate the high-efficiency performance. The rectification efficiencies of 74.9% and 80.7% are measured for 11.2- and 6 W-input powers at 1.9 GHz, respectively.

High Efficiency Continuous Inverse Class-F Power Amplifier with Modified Current Waveform

Abstract Continuous inverse class-F (CICF) is a recent mode of harmonically-tuned RF power amplifiers used to extend the operating bandwidth of the conventional narrowband class-F−1 power amplifier by producing variable set of drain current waveforms and load admittances that give the same operating efficiency. In this work, a new approach of analysis is developed by suggesting some modified drain current waveforms and comparing the resulting theoretical performance characteristics such as drain efficiency and output RF power with the conventional type. It has been shown that the drain current with a truncated square wave shape can better model the actual behavior of the power amplifier, delivering a theoretical efficiency higher by about 8% than the conventional shape. Besides, a simple analytic technique for extracting the device harmonic load impedances for the desired band is also presented. Based on the theoretical analysis, a 6 W power amplifier circuit was designed and simulated to operate within the frequency band 800 – 1000 MHz. Simulation results indicated that a drain efficiency of values between 82% and 86% was obtained across the specified band.

Extended Inverse Class-F Continuum for Designing Broadband Power Amplifier

The impedance space of the continuous inverse class-F power amplifier (PA) is extended in this paper. Traditionally, for extending impedance space, a reactive term is introduced into the current waveform of the continuous inverse class-F PA. In this paper, two reactive terms are introduced into the current and voltage waveforms simultaneously. The proposed method results in an expansive impedance space for designing broadband continuous inverse class-F PAs. For validating the proposed theory, a broadband PA working over 1.2–4.0[Formula: see text]GHz is designed and fabricated. Experimental results indicate that the fabricated broadband PA delivers a saturation power of 40.2–42.8[Formula: see text]dBm and a drain efficiency of 50.7–69%.

Highly efficient broadband continuous inverse Class‐F power amplifier using multistage second harmonic control output matching network

A multistage second harmonic control output matching network is proposed in this article. Through the fundamental and harmonic impedance matching at multiple frequencies in the target band, the accuracy of the fundamental and harmonic impedance of the continuous power amplifier is improved. The efficiency is improved consequently. A highly efficient broadband continuous inverse Class-F power amplifier based on this structure is designed and fabricated using a CGH40010F GaN HEMT packaged device. The measurement results demonstrate that drain efficiency of 71% to 82% and output power of 40.1 to 41.5 dBm is achieved with more than 10 dB gain across 1.35 to 2.35 GHz.

Extended Continuous Inverse Class-F Power Amplifiers With Class-AB Bias Conditions

In this letter, the operation of continuous inverse Class-F (Class-F−1) mode with Class-AB bias conditions is modeled. The extended waveform expression of intrinsic drain current is derived for continuous Class-F−1 power amplifiers (PAs) biased above pinchoff point. Based on the modified current and voltage waveform formulas, the delivered power and efficiency performance is analyzed as a function of conduction angle. Moreover, the design space of fundamental and harmonic load admittances is generalized for any conduction angle between $\pi $ and $2\pi $ . For experimental verification, a broadband PA is implemented with a 6-W LDMOS device. Under a Class-AB bias condition, the fabricated PA exhibits more than 70% power added efficiency and 38-dBm output power with a fractional bandwidth of 62% from 500 to 950 MHz.

Highly Efficient Broadband Continuous Inverse Class-F Power Amplifier Design Using Modified Elliptic Low-Pass Filtering Matching Network

This paper proposes a design approach for a broadband and high-efficiency continuous inverse Class-F ( ${\text {CCF}}^{-1}$ ) power amplifier (PA) based on a modified elliptic low-pass filtering (LPF) matching network (MN). From theoretical and practical perspectives, the importance of a swift impedance transition from the higher end of the fundamental frequency band to the lower end of the second harmonic band is discussed, when designing a broadband single-mode PA. After being compared with widely used Chebyshev LPF MNs, a modified elliptic LPF MN, which provides a sharp roll-off, is utilized to provide the required rapid transition. A step-by-step design procedure of the proposed modified elliptic LPF MN is presented. Experimental results show that a high-efficiency ${\text {CCF}}^{-1}$ PA is realized from 1.35 to 2.5 GHz (fractional bandwidth = 60%) with measured drain efficiency of 68%–82% and output power of 41.1–42.5 dBm. When stimulated by a 20-MHz LTE signal with an average output power of approximately 34.5 dBm, the proposed PA, combined with digital pre-distortion, achieved adjacent channel leakage ratios (ACLRs) below $-{\text {45 dBc}}$ , with average efficiency (AE) ranging from 37% to 45.8%. Similar performance is measured when the proposed PA is driven by a dual-band dual-mode modulated signal with a 100-MHz instantaneous bandwidth at a center frequency of 2.14 GHz.

Design of Broadband Highly Efficient Harmonic-Tuned Power Amplifier Using In-Band Continuous Class-${\hbox{F}}^{-1}/{\hbox{F}}$ Mode Transferring

A novel methodology for designing high-frequency broadband harmonic-tuned power amplifiers (PAs) is presented in this paper. Specifically, a hybrid PA mode, transferring between continuous inverse Class-F and continuous Class-F, is for the first time employed to design PAs with optimal performance over more than-an-octave bandwidth. A GaN PA is designed and realized based on this mode-transferring operation using a three-stage transmission-line-based low-pass matching network. Simulation and experimental results show that an in-band PA-mode transferring between continuous Class- F-1 and continuous Class-F is successfully performed. The implemented PA achieves a measured 87% bandwidth from 1.3 to 3.3 GHz, while exhibiting a state-of-the-art performance of >;10-dB gain, 60%-84% efficiency, and 10-W output power throughout this band. Furthermore, modulated evaluation is carried out using a 300-kHz bandwidth 16-quadrature amplitude-modulation signal. Good linearity performance is measured with adjacent channel power ratio from -20 to -35 dBc and an error vector magnitude of 4%-9% over the entire bandwidth.

The Continuous Inverse Class-F Mode With Resistive Second-Harmonic Impedance

In this paper, an extended version of the continuous class-F-1 mode power amplifier (PA) design approach is presented. A new formulation describing the current waveform in terms of just two additional parameters, while maintaining a constant half-wave rectified sinusoidal voltage waveform, allows multiple solutions of fundamental and second-harmonic impedances that provide optimum performance to be computed. By varying only the imaginary parts of fundamental and second-harmonic impedances, it is shown that output performance in terms of power and efficiency is maintained constant and equal to that achievable from the standard class-F-1 . Indeed, when presenting resistive second-harmonic impedances, it will be demonstrated that the fundamental load can be adjusted to maintain satisfactory output performances greater than a certain predetermined target value. The measurements, conducted on a GaAs pHEMT device at 1 GHz, show a good agreement with the theoretical analysis, revealing drain efficiencies greater than 70% for a very large range of load solutions, which can translate to an ability to accommodate reactive impedance variations with frequency when designing broadband PAs.