Feedback analysis and design of inductive power links driven by Class-E amplifiers with variable coupling coefficients

The efficiency of inductive power links driven by Class-E amplifiers may deteriorate due to variation in the coupling coefficient when the relative position of the radio frequency (RF) coils changes.To solve this problem,a new design methodology of power links is presented in this paper.The aim of the new design is to use the feedback signal,which is a phase difference between the driving signal and the output current of the Class-E amplifier,to adjust the duty cycle and angular frequency of the driving signal to maintain the optimum state of the inductive power link,and to adjust the supply voltage to keep the output power constant when the coupling coefficient of the RF coils changes.The parameter adjustments with respect to the coupling coefficient and the feedback signal are derived from the design equation of the inductive power link.To validate the feedback control rules,a prototype of the inductive power link was constructed,and its performance validated with the coupling coefficient set at 0.2 and a duty cycle of 0.5.The experimental results showed that,by adjusting the duty cycle,the angular frequency,and the supply voltage,the power link can be kept in optimal operation with a constant output power when the coupling coefficient changes from 0.2 to 0.1 to 0.25.

Design of CMOS class-E power amplifier for low power applications

A fully integrated class-E power amplifier（PA） at 2.4 GHz implemented in a 0. 18 μm 6-metal-layer mixed/RF CMOS （ complementary metal-oxide-semiconductor transistor ） technology is presented. A two-stage amplification structure is chosen for this PA. The driving stage produces a high swing switch signal by using resonation technology. The output stage is designed as a class-E topology to realize the power amplification. Under a 1.2 V power supply, the PA delivers a maximum output power of 8. 8 dBm with a power-added efficiency （PAE） of 44%. A new power control method for the class-E power amplifier is described. By changing the amplitude and duty cycle of the signal which enters the class-E switch transistor, the output power can be covered from - 3 to 8. 8 dBm through a three-bit control word. The proposed PA can be used in low power applications, such as wireless sensor networks and biotelemetry systems.

A 1.8 GHz Power Amplifier Class-E with Good Average Power Added Efficiency

This paper presents a 1.8 GHz class-E controlled power amplifier (PA). The proposed power amplifier is designed with two-stage architecture. The main advantage of the proposed technique for output control power is a high 37 dB output power dynamic range with good average power adding efficiency. The measurement results show that the PA achieves a high power gain of 23 dBm and power added efficiency (PAE) by 38%. The circuit was post layout simulated in a standard 0.18 μm CMOS technology.

Highly efficient class-F power amplifier with digital predistortion for WCDMA applications

A digital predistorted class-F power amplifier （PA） using Cree GaN HEMT CGH40010 operating at 2. 12 GHz is presented to obtain high efficiency and excellent linearity for wideband code-division multiple access （ WCDMA ） applications. Measurement results with the continuous wave （CW） signals indicate that the designed class-F PA achieves a peak power-added efficiency （PAE） of 75. 2% with an output power of 39.4 dBm. The adjacent channel power ratio （ACPR） of the designed PA after digital predistortion （DPD） decreases from -28. 3 and -27. 5 dBc to -51.9 and -54. 0 dBc, respectively, for a 4-carrier 20 MHz WCDMA signal with 7. 1 dB peak to average power ratio （PAPR）. The drain efficiency （DE） of the PA is 37. 8% at an average output power of 33. 3 dBm. The designed power amplifier can be aoolied in the WCDMA system.

High-Power Raman Soliton Generation at 1.7 μm in All-Fiber Polarization-Maintaining Erbium-Doped Amplifier

An all-fiber polarization maintaining high-power laser system operating at 1.7 μm based on the Ramaninduced soliton self-frequency shifting effect is demonstrated. The entirely fiberized system is built by erbiumdoped oscillator and two-stage amplifiers with polarization maintaining commercial silica fibers and devices, which can provide robust and stable soliton generation. High-power soliton laser with the average power of 0.28 W,the repetition rate of 42.7 MHz, and pulse duration of 515 fs is generated directly from the main amplifier.Our experiment provides a feasible method for high-power all-fiber polarization maintaining femtosecond laser generation working at 1.7 μm.

Broadband Dual-Input Doherty Power Amplifier Design Based on a Simple Adaptive Power Dividing Ratio Function

In this paper,a simple adaptive power dividing function for the design of a dual-input Doherty power amplifier(DPA)is presented.In the presented approaches,the signal separation function(SSF)at different frequency points can be characterized by a polynomial.And in the practical test,the coefficients of SSF can be determined by measuring a small number of data points of input power.Same as other dualinput DPAs,the proposed approach can also achieve high output power and back-off efficiency in a broadband operation band by adjusting the power distribution ratio flexibly.Finally,a 1.5-2.5 GHz highefficiency dual-input Doherty power amplifier is implemented according to this approach.The test results show that the peak power is 48.6-49.7d Bm,and the 6-d B back-off efficiency is 51.0-67.0%,and the saturation efficiency is 52.4-74.6%.The digital predistortion correction is carried out at the frequency points of 1.8/2.1GHz,and the adjacent channel power ratio is lower than-54.5d Bc.Simulation and experiment results can verify the effectiveness and correctness of the proposed method.

A Hybrid Integrated and Low-Cost Multi-Chip Broadband Doherty Power Amplifier Module for 5G Massive MIMO Application

In this paper,a hybrid integrated broadband Doherty power amplifier(DPA)based on a multi-chip module(MCM),whose active devices are fabricated using the gallium nitride(GaN)process and whose passive circuits are fabricated using the gallium arsenide(GaAs)integrated passive device(IPD)process,is proposed for 5G massive multiple-input multiple-output(MIMO)application.An inverted DPA structure with a low-Q output network is proposed to achieve better bandwidth performance,and a single-driver architecture is adopted for a chip with high gain and small area.The proposed DPA has a bandwidth of 4.4-5.0 GHz that can achieve a saturation of more than 45.0 dBm.The gain compression from 37 dBm to saturation power is less than 4 dB,and the average power-added efficiency(PAE)is 36.3%with an 8.5 dB peak-to-average power ratio(PAPR)in 4.5-5.0 GHz.The measured adjacent channel power ratio(ACPR)is better than50 dBc after digital predistortion(DPD),exhibiting satisfactory linearity.

Harmonic balance simulation of the influence of component uniformity and reliability on the performance of a Josephson traveling wave parametric amplifier

A Josephson traveling wave parametric amplifier(JTWPA),which is a quantum-limited amplifier with high gain and large bandwidth,is the core device of large-scale measurement and control systems for quantum computing.A typical JTWPA consists of thousands of Josephson junctions connected in series to form a transmission line and hundreds of shunt LC resonators periodically loaded along the line for phase matching.Because the variation of these capacitors and inductors can be detrimental to their high-frequency characteristics,the fabrication of a JTWPA typically necessitates precise processing equipment.To guide the fabrication process and further improve the design for manufacturability,it is necessary to understand how each electronic component affects the amplifier.In this paper,we use the harmonic balance method to conduct a comprehensive study on the impact of nonuniformity and fabrication yield of the electronic components on the performance of a JTWPA.The results provide insightful and scientific guidance for device design and fabrication processes.

Three-channel CMOS transimpedance amplifier for LiDAR sensor receiver

For time-of-flight(TOF)light detection and ranging(LiDAR),a three-channel high-performance transimpedance amplifier(TIA)with high immunity to input load capacitance is presented.A regulated cascade(RGC)as the input stage is at the core of the complementary metal oxide semiconductor(CMOS)circuit chip,giving it more immunity to input photodiode detectors.A simple smart output interface acting as a feedback structure,which is rarely found in other designs,reduces the chip size and power consumption simultaneously.The circuit is designed using a 0.5μm CMOS process technology to achieve low cost.The device delivers a 33.87 dB?transimpedance gain at 350 MHz.With a higher input load capacitance,it shows a-3 dB bandwidth of 461 MHz,indicating a better detector tolerance at the front end of the system.Under a 3.3 V supply voltage,the device consumes 5.2 mW,and the total chip area with three channels is 402.8×597.0μm2(including the test pads).

Channel estimation in integrated radar and communication systems with power amplifier distortion

To reduce the negative impact of the power amplifier(PA)nonlinear distortion caused by the orthogonal frequency division multiplexing(OFDM)waveform with high peak-to-average power ratio(PAPR)in integrated radar and communication(RadCom)systems is studied,the channel estimation in passive sensing scenarios.Adaptive channel estimation methods are proposed based on different pilot patterns,considering nonlinear distortion and channel sparsity.The proposed methods achieve sparse channel results by manipulating the least squares(LS)frequency-domain channel estimation results to preserve the most significant taps.The decision-aided method is used to optimize the sparse channel results to reduce the effect of nonlinear distortion.Numerical results show that the channel estimation performance of the proposed methods is better than that of the conventional methods under different pilot patterns.In addition,the bit error rate performance in communication and passive radar detection performance show that the proposed methods have good comprehensive performance.

Analysis of the third harmonic for class-F power amplifiers with an Ⅰ–Ⅴ knee effect

The appearance of third-generation semiconductors represented by gallium nitride （GaN） material greatly improves the output power of a power amplifier （PA）, but the efficiency of the PA needs to be further improved. The Class-F PA reduces the overlap of drain voltage and current by tuning harmonic impedance so that high efficiency is achieved. This paper begins with the principle of class-F PA, regards the third harmonic voltage as an independent variable, analyzes the influence of the third harmonic on fundamental, and points out how drain efficiency and output power vary with the third harmonic voltage with an I-V knee effect. Finally, the best third harmonic impedance is found mathematically. We compare our results with the Loadpull technique in advanced design system environment and conclude that an optimized third harmonic impedance is open in an ideal case, while it is not at an open point with the I-V knee effect, and the drain efficiency with optimized third harmonic impedance is 4% higher than that with the third harmonic open.

Using LDMOS Transistor in Class-F Power Amplifier For WCDMA Applications

The fundamental operating principle of a Class F power amplifier and the factors aiding or affecting Class F performance were explicated previously. A Class F power amplifier design which satisfies WCDMA specifications is explained in this paper. The Class F amplifier was designed by employing Motorola’s LDMOS (Laterally Diffused Metal Oxide Semiconductor) transistor models and we simulated its performance by means of ADS. A variety of procedures were applied in the process of designing Class F amplifier, namely, DC simulation, bias point selection, source-pull and load-pull characterization, input and output matching circuit design and the design of suitable harmonic traps, which are explained here.

X-band inverse class-F GaN internally-matched power amplifier

An X-band inverse class-F power amplifier is realized by a 1-mm Al Ga N/Ga N high electron mobility transistor（HEMT）.The intrinsic and parasitic components inside the transistor,especially output capacitor Cds,influence the harmonic impedance heavily at the X-band,so compensation design is used for meeting the harmonic condition of inverse class-F on the current source plane.Experiment results show that,in the continuous-wave mode,the power amplifier achieves 61.7% power added efficiency（PAE）,which is 16.3% higher than the class-AB power amplifier realized by the same kind of HEMT.To the best of our knowledge,this is the first inverse class-F Ga N internally-matched power amplifier,and the PAE is quite high at the X-band.

Switching Optimization for Class-G Audio Amplifiers with Two Power Supplies

This paper presents a system-level method to decrease the power consumption of integrated audio Class-G amplifiers for mobile phones by using the same implementation of the level detector, but by changing the parameters of the switching algorithm. This method uses an optimization based on a simplified model simulation to quickly find the best power supply switching strategy in order to decrease the losses of the internal Class-AB amplifier. Using a few relevant equations of Class-G on the electrical level and by reducing the number of calculation points, this model can dramatically reduce the calculation time to allow power consumption evaluation in realistic case conditions compared to the currently available tools. This simplified model also evaluates the audio quality reproduction thanks to a psycho-acoustic method. The model has been validated by comparing model results and practical measurements on two industrial circuits. This proposed model is used by an optimizer based on a genetic algorithm associated with a pattern search algorithm to find the best power supply switching strategy for the internal Class-AB amplifier. The optimization results improve life-time performance by saving at least 25% in power consumption for typical use-case (1mW) compared to the industrial circuit studied and without losses in audio quality.

Step memory polynomial predistorter for power amplifiers with memory

To reduce the number of digital predistortion coefficients, a step memory polynomial （SMP）predistorter is presented. The number of predistortion coefficients is decreased by adjusting the maximum nonlinear order for different memory orders in the traditional memory polynomial （MP）predistorter. The proposed SNIP predistorter is identified by an offline learning structure on which the coefficients can be extracted directly from the sampled input and output of a PA. Simulation results show that the SMP predistorter is not tied to a particular PA model and is, therefore, robust. The effectiveness of the SMP predistorter is demonstrated by simulations and experiments on an MP model, a parallel Wiener model, a Wiener-Hammerstein model, a sparsedelay memory polynomial model and a real PA which is fabricated based on the Freescale LDMOSFET MRF21030. Compared with the traditional MP predistorter, the SMP predistorter can reduce the number of coefficients by 60%.

Single Event Transients of Operational Amplifier and Optocoupler

The single event transient effects of the operational amplifier LM124J and the optocoupler HCPL 5231 are investigated by a pulsed laser test facility. The relation of transient pulse shape to pulsed laser equivalent LET is tested,the sensitive areas of the SET effects are identified in voltage follower application mode of LM124J, and the mechanism is initially analyzed. The transient amplitude and duration of HCPL5231 at various equivalent LET are examined,and the SET cross-section is measured. The results of our test and heavy ion experimental data coincide closely,indicating that a pulsed laser test facility is a valid tool for single event effect evaluation.

Design Technologies for Silicon-Based High-Efficiency RF Power Amplifiers:A Brief Overview

This paper presents a brief overview of several promising design technologies for high efficiency silicon-based radio frequency （RF） power amplifiers （PAs） as well as the use of these technologies in mobile broadband wireless communications. Four important aspects of PA design are addressed in this paper. First, we look at class-E PA design equations and provide an example of a class-E PA that achieves efficiency of 65-70% at 2.4 GHz. Then, we discuss state-of-the-art envelope tracking （ET） design for monolithic wideband RF mobile transmitter applications. A brief overview of Doherty PA design for the next-generation wireless handset applications is then given. Towards the end of the paper, we discuss an inherently broadband and highly efficient class-J PA design targeting future multi-band multi-standard wireless communication protocols.

All-Optical Sampling Using Nonlinear Polarization Rotation in a Single Semiconductor Optical Amplifier

We propose a novel all-optical sampling method using nonlinear polarization rotation in a semiconductor optical amplifier. A rate-equation model capable of describing the all-optical sampling mechanism is presented in this paper. Based on this model, we investigate the optimized operating parameters of the proposed system by simulating the output intensity of the probe light as functions of the input polarization angle, the phase induced by the polarization controller, and the ori- entation of the polarization beam splitter. The simulated results show that we can obtain a good linear slope and a large linear dynamic range,which is suitable for all-optical sampling. The operating power of the pump light can be less than lmW. The presented all-optical sampling method can potentially operate at a sampling rate up to hundreds GS/s and needs low optical power.

SiGe HBT Class AB Power Amplifier for Wireless Communications

Good performance SiGe power amplifiers applicable to wireless communications are demonstrated.The output power can reach more than 30dBm in class B mode.And in class AB mode,the output power at 1dB compression point ( P 1dB ) is 24dBm,the output third order intercept (TOI) power is 39dBm under V cc of 4V.The highest power added efficiency (PAE) and PAE at 1dB compression point are 34% and 25%,respectively.The adjacent channel power rejection for CDMA signal is more than 42dBc,which complies with IS95 specification.