Power Amplifier Circuit Research Articles

A high efficiency 10W MMIC PA for K-b and satellite communications

AbstractThis paper discusses the design steps and experimental characterization of a monolithic microwave integrated circuit (MMIC) power amplifier developed for the next generation of K-band 17.3–20.2 GHz very high throughput satellites. The technology used is a commercially available 100-nm gate length gallium nitride on silicon process. The chip was developed taking into account the demanding constraints of the spacecraft and, in particular, carefully considering the thermal constraints of such technology, in order to keep the junction temperature in all devices below 160°C in the worst-case condition (i.e., maximum environmental temperature of 85°C). The realized MMIC, based on a three-stage architecture, was first characterized on-wafer in pulsed regime and, subsequently, mounted in a test-jig and characterized under continuous wave operating conditions. In 17.3–20.2 GHz operating bandwidth, the built amplifier provides an output power >40 dBm with a power added efficiency close to 30% (peak >40%) and 22 dB of power gain.

Интегральная оценка параметров усилителя мощности радиопередатчика с автоматической регулировкой режима двухчастотным тестовым сигналом

Comparative estimation of energy parameters of power amplifiers of single-band radio transmitters using automatic mode adjustment using a deterministic two-frequency test signal instead of a random single-band signal modulated by speech is investigated in the work. Relationships are found that allow judging the power consumption of the terminal stage of the power amplifier with automatic mode adjustment under various types of modulation based on the results of measurements obtained during tests. The ratios between the power consumption of the output stage when amplifying the random speech signal and amplifying the deterministic two-frequency test signal are obtained both without taking into account losses in the controlled power supply and taking into account such losses. Method is proposed for calculation of energy gain and efficiency factor (efficiency) when applying automatic control of supply voltage of output cascades of shortwave transmitters intended for modulation with speech signals. The loss in the regulated power supply has been estimated. The advantage of power amplifier circuits with automatic mode adjustment is justified

A Novel Cost-Effective Magnetic Characterization Tool for Soft Magnetic Materials Used in Electrical Machines

Energy losses during the magnetization process of soft magnetic laminations depend on the excitation waveform. Manufacturers of magnetic materials may not provide losses for different excitation waveforms. This may affect the accuracy of the predicted losses which are used to estimate the performance of electrical equipment during the predesign stage. Thus, a characterization tool which is capable of measuring hysteresis loops under controlled magnetization is required. Digital characterization systems available in literature use expensive commercial power amplifiers. In this work, a cost-effective power amplifier circuit is developed and interfaced with a LabVIEW program to characterize soft magnetic materials. The measurements for a sinusoidal excitation from the proposed setup are validated with those from a standard commercial measuring setup. The system is also used to measure hysteresis loops for arbitrary magnetization conditions (magnetic flux density ( B) with harmonics). The proposed setup can operate over a frequency range 35-500 Hz. A small Epstein frame is also designed for measurements at higher frequencies (>200 and <; 500 Hz). A provision is also made to predict three components of dynamic hysteresis losses at any frequency in the above range using the loss separation approach. This capability of the setup enables the user to predict the losses at frequencies beyond the capability of the tool. The predicted losses using this algorithm are validated with measured losses. The proposed setup is cost-effective and can be developed easily using basic electronic components.

Aging in CMOS RF Linear Power Amplifiers: An Experimental Study

An extensive experimental analysis of the hot carrier injection (HCI) and bias temperature instability (BTI) aging effects on RF linear power amplifiers (PAs) is presented in this article. Two different 2.45-GHz PA topologies have been implemented in a CMOS 65-nm technology: one based on a classical common-source (CS) and choke inductor and another one based on a complementary current-reuse (CR) circuit, both of them producing similar gain and output 1-dB compression point (P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1dB</sub> ). These circuits have been stressed to produce accelerated aging degradation, by applying increasing supply (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> ) voltages or increasing RF input powers (PIN). The degradation on the transistor parameters (threshold voltage and mobility), dc bias point (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> current), and RF performance (gain, matching, and compression point) has been simultaneously measured. This has allowed us to observe how the reduced transistor degradation in CR PA results in higher robustness in its RF parameters compared with the CS PA circuit. The equivalent root-mean-square (rms) voltages have been proposed as an observable metric to assess the combined dc + RF stress in a PA circuit. This has been applied to a semianalytical model, providing comprehension of the link between the conditions under which a circuit is operated, the degradation of the transistor parameters, and the effects on the dc current and RF performance.

BH hysteresis measurement system for thin soft magnetic materials

In this work, a computer controlled automated system is designed for the evaluation of magnetic properties of thin soft magnetic materials. Magnetic measurements were conducted using a National Instrument Data Acquisition card, a signal generator, a power amplifier circuit for the signal voltage, and an AD620 voltage amplifier circuit for the induced voltage in the secondary coil. The LabVIEW software was used for controlling the hardware and processing the experimental data points to draft a BH-hysteresis loop for the sample. A dedicated feedback loop algorithm was designed for controlling the waveform of the flux density at the secondary coil during the magnetization process. Based on the results obtained, it is shown that the accuracy of coercivity measurement is increased using the sinusoidal flux density. The high accuracy instrumentation amplifier circuit together with the flux density control feedback loop made it possible to examine the magnetic properties of thin samples.

Research on Constant Current Technology of High Current Power Amplifier for Relay Protection Test Device

In order to provide more accurate and consistent reference current for power system under different loads, the constant current performance of the high-current power amplifier is studied. This paper presents a circuit topology suitable for high-current power amplifier circuits, and analyses the key factors that affect its constant current characteristics. It is found that resistance matching plays a decisive role in the constant current characteristics. Through quantitative analysis and verification, the boundary conditions of the output resistance of the high-current power amplifier under the specified resistance accuracy are also found. Then based on Monte Carlo analysis and worst-case analysis, the previous theoretical derivation afterwards is conducted. Finally, an effective method of resistance matching is brought forward, which is authenticated in the contrast test later.

One-Chip Integration of RF MEMS Switched Capacitor and Power Amplifier Using CMOS-Compatible Post Fabrication Process

This study presents a single-chip integrated reconfigurable 180-nm complementary metal–oxide–semiconductor (CMOS) power amplifier (PA) with a radio frequency micro-electro-mechanical system (RF MEMS) switched capacitor, which is highly useful for advanced wireless mobile communication systems. The proposed reconfigurable PA prototype was designed to support the 0.9, 1.8, 2.4, and 5.0 GHz quad-bands by varying the capacitance values of the RF MEMS switched capacitor at the output matching network. The RF MEMS switched capacitor was post-fabricated on the same silicon substrate with which the PA circuit was integrated using 180-nm CMOS fabrication technology. The entire fabrication step was performed based on a CMOS-compatible low-temperature post process to avoid the performance degradation of the CMOS PA circuit. The fabricated RF MEMS switched capacitor exhibited capacitances of approximately 1.0 and 3.9 pF at a frequency of 0.9 GHz in its OFF and ON states, respectively. The measured output powers of the integrated quad-band PA were 27.13, 26.63, 26.29, and 23.43 dBm at the frequencies of 0.9, 1.8, 2.4, and 5.0 GHz with the continuous-wave signal, 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.

Metal-Embedded Chiplet Assembly for Microwave Integrated Circuits

This letter provides an overview of the metal-embedded chiplet assembly for microwave integrated circuits (MECAMICs) technology. MECAMIC is a 2.5-D wafer-level packaging approach that provides seamless heterogeneous integration capabilities of compound semiconductor transistors (e.g., GaN HEMTs) with passive components and interconnects using a backside metal embedding process. The chiplets are embedded in through-interposer cavities, and the backside metallization locks the chiplets into position while providing dc and RF ground for the high-frequency circuits. With this hybrid manufacturing approach, high-performance RF ICs can: 1) be designed using the best transistor technology for the function; 2) be fabricated in short cycle times through hybrid manufacturing; and 3) compete performancewise with monolithic circuits. We demonstrated an $X$ -band power amplifier circuit realized in MECAMIC with a saturated output power of 31 dB and a peak power added efficiency of 54%, which compared favorably to its monolithic GaN monolithic microwave integrated circuit (MMIC) counterpart. The MECAMIC process cycle time was $4.5\times $ faster than the monolithic process.

Simulation and Experimental Study of Flexible Cooling System Based on Microchannel in PDMS

In this article, a flexible cooling method based on microchannels in polydimethylsiloxane (PDMS) substrate is proposed, for those flexible and conformal circuits or systems. The proposed microchannels with various widths, depths, and quantities were designed and simulated in the software of STAR-CCM+, for performance investigation and prediction of the heat dissipation. The fabricated PDMS with microchannels was surface treated before attaching to an RF power amplifier circuits. By using an infrared thermal imager, the time–temperature curves and heat distribution of the circuit were measured and recorded, under the different cooling conditions of flow rates and microchannels. The main advantages of the proposed cooling concept are the convenience of fabrication, conformality, and flexibility, which indicates that the proposed concept is potentially to be an excellent candidate for cooling solution, to the particular applications of flexible or conformal circuits.

LC resonant circuits based matching networks for continuous mode MMIC power amplifiers

AbstractThis article presents a practical design methodology to construct output matching networks for broadband continuous mode monolithic microwave integrated circuit (MMIC) power amplifiers (PAs). Unlike conventional harmonic manipulation approaches, combinations of parallel and series LC resonant circuits are utilized to build the matching networks as it can generate frequency‐dependent components and locate the varying impedance of continuous mode. With a proper design, the impedance variation in frequency domain can be mapped to the frequency response of the matching network at the fundamental frequency and the second harmonic simultaneously. Matching network design procedures are demonstrated and results show that the frequency response of the network has very good approximation with the desired continuous mode conditions. A prototype PA is implemented on 0.25‐μm gallium nitride (GaN) MMIC process, and tested with both continuous‐wave and modulated signals. Measurement results show 50.82% maximum drain efficiency and 8.5 dB gain can be achieved across the operation bandwidth of 5.4 to 6.4 GHz.

A Methodology and a Metric for the Assessment of the Linearizability of Broadband Nonlinear Doherty Power Amplifiers

This letter proposes a novel methodology and a metric for the assessment of the linearizability of broadband nonlinear power amplifiers (PAs). Validation of the proposed methodology and the proposed metric on two linearized Doherty PAs (DPAs) using digital predistortion (DPD) technique was carried out and it demonstrated the suitability and appropriateness of the new metric. Different from the iterative optimization procedure between the PA circuit design and the DPD algorithm compensation, the proposed method aims to provide a quantitative criterion on the PA linearizability based on its frequency-dependent amplitude modulation (AM)/AM and AM/phase modulation (PM) characteristics. To verify the effectiveness of the metric, two DPAs were characterized before and after a DPD-based linearization. The average correlation coefficients between the values of the metric and the adjacent channel power ratio after DPD were 0.8763 and 0.9156, and that between the values of the metric and the error vector magnitude after DPD were 0.8618 and 0.7200 for PA1 and PA2, respectively, indicating that the evaluation method and the linearizability metric can be used as a good measure to assess the linearizability of broadband PAs.

1-W, High-Gain, High-Efficiency, and Compact Sub-GHz Linear Power Amplifier Employing a 1:1 Transformer Balun in 180-nm CMOS

This letter presents a fully integrated two-stage monolithic microwave integrated circuit (MMIC) power amplifier (PA) with a 1:1 transformer balun in Taiwan Semiconductor Manufacturing Company (TSMC) 180-nm CMOS process. To optimize the performance of PA, an on-chip 1:1 turn spiral transformer balun (STB) was used with a high supply power through the cascode topology. The proposed PA achieved a 40-43-dB gain and a saturation power (P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</sub> ) of 29.9-30.3 dBm with a 40%-45% of power-added efficiency (PAE) in the frequency range of 820-1000 MHz. Using the antiphase biasing technique, the PA achieves a linear output power of 25 dBm with 29.5% PAE in 20-MHz spacing two-tone measurement, which satisfies IMD3 <; -25 dBc. The measured 1-dB compression point was 28.1 dBm. Furthermore, the proposed PA occupied a core area of 3.3 × 0.86 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

A 2–20-GHz 10-W High-Efficiency GaN Power Amplifier Using Reactive Matching Technique

In this article, we present the analysis, design, and implementation of a wideband 10-W monolithic microwave integrated circuit power amplifier (PA), fabricated in a low-cost 0.1-μm gallium nitride (GaN) on Si technology. The design is focused on the realization of a low-loss and wideband impedance transformation networks across 2-20 GHz using a reactive matching (RM) technique. The two-stage GaN PA achieves an average output power of 40.1 dBm and a peak output power of 41.6 dBm at 13 GHz, in the CW-mode operation, with a smallsignal gain of S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> > 25.5 dB over the entire bandwidth. The average power-added efficiency (PAE) is 21%, with a peak PAE of 29% at 6 GHz. The PA chip occupies an area of 2.9×2.6 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . To the best of our knowledge, the PA presented in this work demonstrates the highest broadband gain among the reported GaN-based RMPAs with a corresponding output power of about 10 W.

Circuit efficiency of high power amplifier circuit

In this paper, an equation of circuit efficiency (CE) of a power amplifier (PA) circuit is proposed and verified first time. To perform this work, a class F PA is considered, a simple Pi-output matching network (OMN) is proposed for low network loss. It is the first time where the equation of drain efficiency(DE) is investigated in a realistic situation by considering the parasitic effects of the transistor. A high voltage GaN HEMT CGH40010F device is adopted in design and simulation. The 0.9 GHz is selected as the operating frequency of the power amplifier (PA) circuit just for validation and comparison purposes. The proposed OMN gives only 3% power loss due to its simple structure. The proposed realistic drain efficiency (RDE) is well matched with the simulated drain efficiency (DE) result. The theoretical circuit efficiency (CE) of 74.7% is well matched with the simulated value of 73.1% at 0.9 GHz. The circuit efficiency (CE) and output power (Pout) of the proposed PA circuit are 54%-78.5% and 39-41.2 dBm across 0.22–1.18 GHz.

Design of Broadband 1.9 GHz Ga as MMIC Switching Power Amplifier for PCS Communication Services

The paper presents a broadband Monolithic microwave Switching Class–E Power amplifier using 0.5μm GaAs E-pHEMT technology for PCS communications systems operating at 1900MHz.Wider bandwidth is achieved by employing reactance compensation technique in load network of the switching power amplifier. The main Power amplifier is a single stage Class-E circuit with a driver stage driving it to achieve high gain and efficiency. The modified load network using reactance compensation network results in higher power added efficiency. The paper provides simulation results of designed two-stage Class-E Power amplifier circuit results with an power output of 20dBm, power added efficiency of 80% and gain of 26dB at the centre frequency of 1.9GHz compared with various Class-E designs of 1.9 GHz using different technologies. A high linear gain is reported in the design at the frequency range of 0.8GHz to 2.2GHz.The designed circuit achieves a wider bandwidth of 1.35GHz over a frequency range of 0.8-2.2GHz.The physical layout is drawn using GaAs foundry components and EM simulation is performed.

Design of Intravascular Ultrasound-enhanced Thrombolysis Excitation System Based on FPGA

An intravascular ultrasound-enhanced thrombolysis excitation system with adjustable frequency, amplitude and duty cycle was designed based on FPGA (ZYNQ-7Z020). Firstly, the FPGA generated waveform amplitude binary data based on direct digital frequency synthesis (DDS) technology, and then the data was converted into burst signal through an external daughter card, which included D/A conversion circuit, active low-pass filter, power amplifier circuit and impedance matching circuit. The test results demonstrated that the output waveform reached the target with advantages of simple implementation and flexible control, the peak negative pressure generated from ultrasound transducer was doubled by means of an electrical impedance matching network. In vitro thrombus models were applied to verify the excitation system, it turned out that ultrasound cavitation effect generated could accelerate the penetration of urokinase and increase the thrombolysis rate by about 20%.

An Analytic Design Approach to Inverse Class-F RF Power Amplifiers

The design of high efficiency inverse class-F (class-F-1) radio frequency (RF) power amplifiers includes extensive measurements to characterize the RF power device by means of the empirical load-pull test setup. This paper presents an alternative characterization approach based on evaluating the load impedances analytically at the desired harmonic frequencies for a high electron mobility transistor (HEMT) in terms of the internal and package elements of the active device. It additionally provides a method for extracting the parasitic elements of the power device as well as determining the optimum load-line resistance using the transistor manufacturer’s large signal model. A new topology for the output matching circuit is also proposed with its synthetic procedure to present the appropriate harmonic load impedances. To verify this methodology, a 900 MHz inverse class-F power amplifier circuit was designed and its performance was tested with the aid of the Keysight ADS software. The simulation results showed an output power of 38 dBm, a power gain of about 13 dB, DC-to-RF efficiency greater than 87%, and an acceptable level of linearity for both GSM and CDMA modulated signals.

Design of WPT RF Power Supply Based on Dual Directional Coupler and Capacitor Array Impedance Matching Network

In the engineering use of a magnetically coupled resonant radio energy transmission system, both the resonant frequency and the optimal load impedance will be varied because of the external conditions. In view of the above problems, this paper proposes an RF power supply with adjustable frequency and optimal load impedance, in order to achieve efficient power transmission for different frequency radio energy transmission systems and different load conditions. The RF power supply is mainly composed of a frequency controllable signal generator, a Class E power amplifier circuit, a dynamic impedance matching network, a load detection circuit and a controller. Through the above parts, the load tracking of the RF power supply can be realized, and the higher output efficiency can be realized under the condition of changing the working frequency and the load. Finally, the feasibility of the proposed RF power supply is verified through experiments. The experimental results show that the RF power supply can automatically track changes in the operating frequency and load range, and the output efficiency can be maintained at more than 75%.

Energy-Efficient Adaptive Modulation and Data Schedule for Delay-Sensitive Wireless Communications

In this paper, targeting at improving the energy efficiency (EE) for Quality-of-Service (QoS)-guaranteed wireless communications, we develop new adaptive modulation and data scheduling algorithms for delay-sensitive bursty data. Assuming a-priori knowledge on data arrivals and latency requirements, the problem is formulated as a mix-integer programming that minimizes the total energy consumption at the transmitter with a non-linear Doherty power amplifier (PA) and non-negligible circuit power. According to the different properties of the PA in different output power regions, we decouple the formulated problem and solve it in two stages. In the first stage, assuming the PA has a linear efficiency, we develop an optimal modulation and data scheduling scheme (MDS) relying on convex relaxation and the resultant optimality conditions. The MDS is able to reveal the specific structure of the optimal policy in a computationally efficient and graphical manner. On top of that, a heuristic MDS scheme (HMDS) is proposed to adjust the MDS when the PA works in the non-linear region in the second stage, where a quadratic function is obtained to approximate the non-linear PA model. The offline HMDS algorithm is further extended to practical online scenarios in a well-structured way, where the modulation and data scheduling policy is produced on-the-fly. Simulation corroborates that the proposed offline algorithm can achieve the exactly same performance as the standard CVX solver, while requiring only 0.69% of its computational time.