Simplified Real Frequency Technique Research Articles

3.3-4.3 GHz efficient continuous class-F gallium nitride power amplifier based on simplified real frequency technique and harmonic tuning.

In order to implement the fifth generation (5G) communication system for a large number of users, the governments of many countries nominated the low 5G frequency band between 3.3 and 4.3 GHz. This paper proposes a wideband RFPA by designing the input matching network (MN) and output MN of the device using the simplified real frequency technique (SRFT) and the harmonic tuning network. The load-pull and source-pull is applied at multiple points for 100 MHz intervals over the bandwidth to obtain the optimum impedances at the output and input of the 10W Gallium Nitride (GaN) Cree CGH40010F device. To verify the design, the RFPA is simulated, and the performance is measured between 3.3 and 4.3 GHz. According to experimental findings, the measured drain efficiency (DE) throughout the whole bandwidth ranged from 57.5 to 67.5% at the output power of 40 dBm. Moreover, at the 1 dB compression point between 39.2 and 42.2 dBm output power, the drain efficiency (DE) achieves a high value of 81.2% with an output power of 42.2 dBm at a frequency of 3.3 GHz. The RFPA can obtain a maximum gain of 12.4 dB at 3.5 GHz. The linearity of the RFPA with a two-tone signal is measured and the value is less than -22 dBc all over the band.

Design of dual-band power amplifier based on microstrip coupled-line bandstop filter

This article presents a simple and effective method for designing a dual-band power amplifier (PA). A microstrip coupled-line bandstop filter (BSF) is cascaded with a broadband PA, thus a notched band can be obtained in the wide operating band, realizing a dual-band characteristic of the PA. The simplified real frequency technique (SRFT) is employed to derive a broadband input matching networks covering the requisite frequency band. Appropriate fundamental impedance and second harmonic impedance matching are achieved at the ideal region of the Smith chart. For validation, an experimental prototype is fabricated and tested using a commercial GaN transistor Cree’s CGH40010F. The proposed dual-band PA is operated at 1.95–2.4 GHz and 2.65–3.1 GHz, with 61%–71% measured power-added efficiency (PAE) and 40.5–41.5 dBm of measured output power.

Design of Impedance Matching Network for Low-Power, Ultra-Wideband Applications

This paper addresses the design of ultra-wideband (UWB) impedance matching networks operating in the unlicensed 3.1–10.6 GHz frequency band for low-power applications. It improves the simplified real frequency technique (SRFT) by adding a realizability check and employing an iterative approach with different initial guesses in optimization to achieve realizable solutions under the requirements of UWB, low-power consumption, and a minimum number of circuit components. The comparison of solutions obtained using the SRFT with published solutions based on the Chebyshev filter theory is presented. It is shown that the optimal SRFT solution requires fewer components in the impedance matching network, maximizes the RF power delivery over the UWB spectrum with a reflection coefficient below −10 dB, and allows for circuit optimization to reduce power consumption. Using the improved SRFT, it demonstrates a systematic approach to find the strategies and limitations of designing the input matching networks for low-power UWB applications using GlobalFoundries 90 nm BiCMOS technology.

Design and Implementation of a High-Efficiency 45 W Compact Class-J Power Amplifier Based on a Simplified Real Frequency Technique for n77 5G New Radio Applications

Design and Implementation of a High-Efficiency 45 W Compact Class-J Power Amplifier Based on a Simplified Real Frequency Technique for n77 5G New Radio Applications

Quality factor based transducer power gain expression

PurposeIn the literature, while designing broadband matching networks, transducer power gain (TPG) is used to measure the transferred power. Generally, in TPG expressions, load and back-end impedances of the matching network are used. This study aims to derive a new quality factor-based TPG expression.Design/methodology/approachIn deriving the new expression, narrowband L type-matching network design approach is used and the new expression in terms of back-end quality factor, load quality factor and output port quality factor is obtained. Then, a broadband-matching network design approach using the derived TPG expression is proposed.FindingsTwo broadband double-matching networks are designed by using the proposed design approach using the derived TPG expression. Performances of the designed-matching networks are compared with the performances of the matching networks designed by means of simplified real frequency technique which is a well-known technique in the literature, and it is shown that they are nearly the same.Originality/valueIn broadband-matching problems, generally an impedance-based TPG expression is used, and it must be satisfied by the designed broadband-matching networks. But, in the literature, there is no quality factor-based TPG expression that can be used in broadband-matching problems. So, this gap in the literature has been filled by this paper.

Design of a C-Band High Efficiency Power Amplifier With Compact Harmonic Control Network

In this letter, the design of a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> -band high-efficiency power amplifier (PA) with a compact harmonic control network (HCN) is presented. Based on the device model, the optimal fundamental and second harmonic load impedance was obtained by load-pull simulation. Then a simply fundamental matching network (FMN) is realized using the simplified real frequency technique (SRFT). To improve efficiency, a compact HCN based on a predesigned FMN is proposed. Besides, the microstrip radial stub (MRS) is used instead of the microstrip open-circuited stub to reduce the loss. A high-efficiency PA working across 6.1–7.2 GHz is simulated and fabricated. Experimental results show that the fabricated PA delivers a saturated output power of 38.2–39.3 dBm with a drain efficiency (DE) of 43%–63.4% in the interested band.

Automatic Methodology for Wideband Power Amplifier Design

This letter presents an automatic power amplifier (PA) design methodology that uses a multidimensional search algorithm to find the best compromise between fundamental and harmonic impedance terminations for a specified bandwidth. In conventional design methodologies, PA designers need to preselect the optimum impedances, which normally follow non-Foster trajectories, and are thus impossible to achieve with passive matching networks (MNs) for a wide frequency range. Instead, the proposed automatic design method directly synthesizes the MNs to achieve the desired output power, efficiency, and gain performance, without forcing any impedance profiles. For that, load-pull data are interpolated using artificial neural networks and an algorithm based on the simplified real frequency technique is used to obtain the MNs. Finally, the method is validated with a single-ended PA implementation.

A high-efficiency continuous class-F power amplifier design using simplified real frequency technique

The fourth-generation (4G) wireless communication has been deployed in many countries. However, there are still some problems such as spectrum crisis due to the increase of wireless mobile devices and servicing. Therefore, the fifth-generation (5G) communication system will be employed at some different spectrum other than 4G frequency band. The radio frequency power amplifier (RFPA) is the key component of the 5G system. In this paper, a broadband continuous class-F (CCF) RFPA is designed for the 5G frequency band from 3.3-4.3 GHz. The input and output matching network are designed using the simplified real frequency technique (SRFT). Using a 10W GaN CGH40010F Cree device, the efficiency of the RFPA achieved greater than 70.7% for the whole frequency band with a maximum of 81.5%. The output power and the gain are more than 40 dBm and 10 dB respectively

A novel direct matching network synthesis technique and its application to broadbandclass‐Jpower amplifier

A novel direct matching network (MN) synthesis method improving the conventional simplified real frequency technique (SRFT) is presented in this article. By straightforwardly optimize the characteristic impedance (physical width) and electrical length (physical length) of each distributed element in a preselected configuration, the proposed method has one more degree of design freedom by comparison with the SRFT, and therefore increases design flexibility and matching effects. To demonstrate its effectiveness, a broadband class-J power amplifier (PA) is devised for which both the input and output MNs are realized using the proposed method. The simultaneous manipulation of fundamental and second harmonic impedances is successfully realized by defining a novel target function that indicates the degree of proximity for the realized impedances to the optimal transistor impedances. Comprehensive equations and complete design procedures of the new technique are given. The measured class-J PA implemented for verification achieves an output power of 39.2 to 42.3 dBm and power-added efficiency of 61.8% to 71.6% over the frequency range of 2.5 to 3.8 GHz using a 10-W GaN HEMT. A 20-MHz LTE-A signal is employed to validate the linearization capability of this class-J PA. An adjacent channel leakage ratio level around −43.8 dBc is achieved after utilizing digital predistortion technique.

Design of a 1–2.8-GHz 100-W Power Amplifier With Bounded Performance Technique

This paper presents the design of a broadband and high-power amplifier with bounded performance technique (BPT). Like the real frequency technique (RFT) or the simplified RFT (SRFT), BPT achieves broadband performance via matching at some in-band discrete real frequencies. It solves some design issues that are not addressed in the RFT and the SRFT. Among them are the inclusion of the design specifications in the device selection and design process and the possible degradation of operation metrics that are not optimized. BPT also avoids complicated analytic mathematics by using circuit prototypes. In this paper, we show the design of an amplifier with BPT. It has a 3-dB compression power of at least 100 W and a drain efficiency of at least 50% over the band 1–2.8 GHz or 94.7% fractional bandwidth. We also show the design of the same amplifier with the traditional SRFT and compare its expected performance with that designed with BPT.

Research of SRFT improving and antenna broadband matching based on the IWO–LM algorithm

This study proposes two modifications to the classical simplified real frequency technique (SRFT). A hybrid algorithm called invasive weed optimisation Levenberg-Marquardt (IWO-LM) algorithm, which combines the IWO and the LM algorithm, is used to optimise the transducer power gain. So the stochasticity of the IWO is introduced to the classical SRFT, the matching result will not be limited by the initial values. Moreover, an additional programme is added to the classical SRFT, which can transform the lumped matching network to the corresponding microstrip circuit. This improved SRFT is used to design a broadband matching network for a printed dipole base station antenna and compared with the classical SRFT, and the corresponding results show that the improved SRFT is less affected by initial values under the similar matching effect. The microstrip matching network and the antenna are integrated together, and then they are fabricated depending on the simulation. The test result of a vector network analyser shows that the bandwidth after matching is 0.728-1.01 GHz and the relative bandwidth is 32.45%, which is improved by 69.98% compared with the unmatched one.

FSRFT Based Broadband Double Matching via Passband Extremums Determination

Fast simplified real frequency technique (FSRFT) is a numerical solver used to solve microwave broadband double-matching (DM) circuit design problems in a much faster and effective manner. Recently, it has been reported that an FSRFT based Matlab code can complete the design of a order lowpass lumped element double matching network to match a given generator and load impedance within an optimization time of only 0.6 seconds, a 47 fold less time than that of the same design done using the classical simplified real frequency technique (SRFT). FSRFT owes this superior speed performance to the fact that it tracks only (system unknowns plus 1) number of passband extremum points selected from among the number of gain data (). This work introduces a simple numerical technique called PED (passband extremums determination technique) to be used in determination of these passband extremum points (PEs). An exemplary order microwave bandpass DM circuit design using FSRFT based Matlab (of Mathworks Inc.) code and the simulation of this design via MWO (of AWR Corp.) has yielded the same circuit performance with an exact agreement. Thus, FSRFT, equipped with the PED, newly proposed hereby, might be used as a powerful solver in designing broadband circuits in many fields such as RF/microwave, radar, and communications.

A New Approach to Design a Broadband Doherty Power Amplifier via Dual-Transformation Real Frequency Technique

A novel dual-transformation simplified real frequency technique is proposed in this paper to synthesize a broadband Doherty power amplifier (DPA). The proposed method can realize the co-design of the carrier and peaking output matching networks to achieve dual-impedance transformation at back-off (BO) and saturation simultaneously. To realize this method, a generalized driving point function with different loads of the matching network is proposed, and weight factors are adopted to combine the separate target functions to form a united one. Compared with conventional designs, no initial guess is required and additional compensating lines are eliminated to improve the performance of the DPA. Based on the proposed technique, a broadband DPA is designed and fabricated across 2.2-3.7 GHz (51% fractional bandwidth). The measurement results show that the designed DPA has a 6-dB BO efficiency of 45%-53% and a saturated output power of 43-44.6 dBm over 1.5 GHz bandwidth. Various modulated signals including 80-MHz long-term evolution-advanced signal and concurrent dual-band signal are employed to validate the DPA. In this way, the DPA can achieve an average efficiency of 45.3%-55.9% at 6.5-dB BO with the adjacent channel leakage ratio levels better than -48.6 dBc by utilizing digital predistortion.

Design of highly efficient broadband harmonic‐optimised GaN power amplifier via modified simplified real frequency technique

A design of broadband power amplifier (PA) which uses harmonic-optimised matching network (MN) is designed to maintain high efficiency. The load–pull data is used to construct the optimal impedance areas in fundamental and harmonic parts. Then, the modified simplified real frequency technique algorithm is employed to design output-MN through constructing the defined harmonic-error functions. A 10 W Cree gallium nitride high-electron-mobility transistor device CGH40010F is used to validate this method. The proposed PA has a 40% bandwidth (1.8–2.7 GHz) and a 64–81% drain efficiency. The digital pre-distortion process shows the adjacent channel leakage ratio (ACLR) is <−52 dBc at 2.25 GHz.

FSRFT—Fast Simplified Real Frequency Technique via Selective Target Data Approach for Broadband Double Matching

This brief introduces a broadband double-matching (DM) solver called fast simplified real frequency technique (FSRFT). FSRFT is essentially a greatly accelerated variant of the well-known classical simplified real frequency technique (SRFT). The basic idea that turns the classical SRFT into a “fast” SRFT relies on two main approaches: the selective target data approach (STDA) and the constraint optimization approach (COA). STDA constructs an optimization target data set formed of only critically selected target data whose element number is equal to or slightly greater than the order of the system unknowns n plus 1, n + 1. In order to exhibit speed performance comparison between SRFT and FSRFT, an example design is considered. An exemplary DM problem, dealing with an n = 6th order low-pass Chebyshev- type equalizer design to match the given generator and load impedances, has been solved by SRFT within 29 s using 90 target data in a typical computer-e.g., Intel 2.20-GHz i7 CPU with 8-GB RAM. On the other hand, the same problem has been solved by the newly proposed FSRFT within only 0.6 s using only n + 1 = 7 critically selected target data in the same computer. FSRFT introduced herein works in any domain, i.e., lumped, distributed, and mixed.

A Broadband Highly Efficient Harmonic-Tuned Power Amplifier Exploiting Compact Matching Network

In this letter, a systematic method to design compact output matching network of power amplifier (PA) is proposed, which is based on the simplified real frequency technique. The produced network is mainly constructed with commensurate transmission lines, containing cascaded unit elements and open-shunt stubs, as well as a shorted-series stub for dc bias. A GaN PA is designed to verify the method. The measured results show that the PA achieves 68.07%–79.49% drain efficiency and 40.93 to 42.4 dBm output power from 1.7 to 3.1 GHz. Moreover, the fabricated PA has a small size of only 2015 mm $^{2}$ , due to the compact matching networks.

Broadband Continuous Class-&lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;${\rm F} ^{-1}$&lt;/tex&gt;&lt;/formula&gt; Amplifier With Modified Harmonic-Controlled Network for Advanced Long Term Evolution Application

This letter presents a highly efficient broadband continuous Class- F <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> power amplifier (PA), which employs the modified simplified real frequency technique (SRFT). In highly efficient PA design, a low-pass matching method is preferred for its harmonic impedance controlling. However, the qualification ( ) in transforming lumped components of filter prototype to transmission lines (TLs) imposes a restriction on its application. To overcome this limitation, a modified SRFT procedure is employed to optimize fundamental impedance and control the harmonic impedance directly with TLs. The proposed design strategy is experimentally verified by a 1.7~2.8 GHz PA design with 80.4% maximum efficiency and 10-W output power. The 100 MHz long term evolution advanced (LTE-A) signal is applied to this PA and the linearization result shows a well -46.4 dBc performance by digital pre-distortion (DPD) at 2.55 GHz.

Systematic design of output filters for audio class-D amplifiers via Simplified Real Frequency Technique

Abstract. In this paper a new filter design concept is proposed and implemented which takes into account the complex loudspeaker impedance. By means of techniques of broadband matching, that has been successfully applied in radio technology, we are able to optimize the reconstruction filter to achieve an overall linear frequency response. Here, a passive filter network is inserted between source and load that matches the complex load impedance to the complex source impedance within a desired frequency range. The design and calculation of the filter is usually done using numerical approximation methods which are known as Real Frequency Techniques (RFT). A first approach to systematic design of reconstruction filters for class-D amplifiers is proposed, using the Simplified Real Frequency Technique (SRFT). Some fundamental considerations are introduced as well as the benefits and challenges of impedance matching between class-D amplifiers and loudspeakers. Current simulation data using MATLAB is presented and supports some first conclusions.

Resistive Second-Harmonic Impedance Continuous Class-F Power Amplifier With Over One Octave Bandwidth for Cognitive Radios

A novel methodology for designing highly-efficient broadband harmonic-tuned power amplifiers (PAs) with more than one octave bandwidth is presented in this paper. Continuous class-F power amplifiers with resistive second-harmonic impedance is for the first time analyzed and employed in a multi-sub-band mode to enhance the bandwidth of a conventional continuous class-F PA. The load-pull method is employed at both fundamental and harmonic frequencies, and the simplified real frequency technique algorithm is used to design and synthesize the PA matching networks. Experimental results show that the fabricated PA operates from 525 to 1325 MHz, with drain efficiency over 70% and output higher than 39 dBm. Digital predistortion is applied to the PA and the adjacent channel power ratio is improved to more than -40 dBc.

A Wideband Doherty Power Amplifier With 100 MHz Instantaneous Bandwidth for LTE-Advanced Applications

In this letter, a 698-862 MHz wideband Doherty power amplifier (DPA) with 100 MHz instantaneous bandwidth is presented. The electrical memory effect of the wideband DPA is reduced by the LC resonant circuits employed in the drain bias networks. The influence of the integrated Doherty combiner is compensated by the broadband output matching networks, which were designed by applying the simplified real frequency technique. Driven with 100 MHz LTE-advanced signals, the adjacent channel leakage ratio (ACLR) and ACLR asymmetry of the proposed DPA at 20 MHz offset are improved by about 4 dB and 3 dB respectively, compared to the wideband DPA with conventional bias networks. After digital predistortion (DPD) linearization, the proposed DPA shows an ACLR of lower than -48 dBc at an average output power of 42.5 dBm, and high drain efficiency of over 42% across the operating frequency range.