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An optimal balance between high efficiency and high linearity is one of the main performance metrics of modern base stations to handle the deep compression of the power amplifier (PA) module. In principle, the plethora of amplitude‐to‐amplitude (AM‐AM) and amplitude‐to‐phase (AM‐PM) distortions are issues worth exploring. Therefore, this paper presents a linearized harmonic‐tuned PA that operates at 2.4 GHz. The presented PA utilizes a compact input matching network (IMN) and output MN (OMN) with shunt‐connected tunable resonant circuits augmented by the stabilization network, whose presence greatly reduces the transistor parasitics and high‐order effects. Hence, a joint embodiment of each other gives optimal fundamental impedance matching alongside harmonic terminations and precise AM/PM waveform properties. The measurement results have shown that the fabricated PA exhibits peak saturated output power of 40.9 dBm and peak drain efficiency (DE) of 67%. In addition, the AM‐AM and AM‐PM curves under continuous‐wave excitation yield a gain flatness of 0.5 dB over a 37.5 dBm power range and ±3.5° phase distortion, respectively, when the input power level is swept up to the saturation level of 40 dBm. When driven with a 5 MHz 64‐QAM OFDM signal and 6.9 dB power back‐off, the manufactured PA meets the adjacent channel leakage ratio specification of −30 dBc at an average output power of 34.5 dBm. [ABSTRACT FROM AUTHOR]

Wire bonding is widely used in various radio frequency (RF) devices and is one of the common forms of signal interconnection. In this article, a new geometric model with related physical parameters is used to describe various actual types of the bondwire, and the corresponding calculation method for the total length of the bondwire is obtained. Consequently, a new equivalent circuit modeling method of the single‐bondwire can be developed and the accuracy of model has been improved. On this basis, using the concept of partial inductance, the modeling method of double‐bondwire is proposed, which can be applied to asymmetric double‐bondwire modeling. The model of bondwire obtained by this modeling method is applied to the design of PA, and the special electrical properties of the bondwire are used to verify a novel harmonic control method, which second and third harmonics could be controlled. The results show that in the Sub‐6G, the proposed bondwire model has good accuracy, and its performance is close to the measured results. The designed PA combined with harmonic control network has good performance, achieving drain efficiency of 62.6%–70% and output power of 40–41.5 dBm at 3.2–3.8 GHz. It is proved that the proposed bonding line modeling method can be applied to the design of high‐efficient PA. [ABSTRACT FROM AUTHOR]

With the increasing demand for large signal bandwidth in communication systems, the complexity of the behavioral model of power amplifier (PA) will also increase. In this paper, a modified weighted magnitude‐selective model based on magnitude‐selective affine (MSA) function based model and weighted memory polynomial model is proposed to ensure low complexity and good modeling performance under broadband signal excitation. This model is constructed by using the power‐dependent weighted function instead of the sum of multiple MSA functions in MSA. It can not only be used to solve the nonlinearity of PA excited by large bandwidth signal but also reducing the model coefficients without affecting the modeling performance makes the digital predistortion of large bandwidth signals more simple and effective. In this paper, a 100 MHz broadband signal is used for simulation and experiment on a wideband PA. The results show that for the same performance the WMA model required approximately 80% less coefficients. [ABSTRACT FROM AUTHOR]

This article presents a broadband fully integrated Doherty power amplifier (DPA) using a continuous-mode combining load. It is illustrated that the continuous-mode impedance condition in back-off and saturation for Doherty operation can be achieved with a simple impedance inverter network (IIN) that can be realized using lumped components in gallium nitride (GaN) monolithic microwave integrated circuits (MMICs). A DPA was designed and fabricated using the 250-nm GaN process to validate the proposed architecture and design methodology. The fabricated DPA chip attains around 8 W saturated power from 4.1 to 5.6 GHz. About 38.5%–46.5% drain efficiencies are achieved at 6-dB output power back-off within the entire design band. When driven by a 100-MHz OFDM signal with 6.5-dB peak-to-average power ratio (PAPR), the proposed DPA achieves better than −45-dBc adjacent channel leakage ratio (ACLR) and higher than 38% average efficiency at 4.4 and 5.2 GHz after digital predistortion. [ABSTRACT FROM AUTHOR]

To cope with the degradation of digital predistortion when bandwidth changes, a bandwidth adaptive behavioral model with dynamic structures for radio frequency (RF) power amplifiers (PAs) is proposed in this article. By applying the nonlinear post‐compensation technology, PA's nonlinearity is decomposed and analyzed. Short‐time Fourier transform and transfer functions are adopted to study the influence of bandwidth variation on the linear memory effect. Based on PA's memory effect analysis, a bandwidth adaptive model with dynamic structures and a coefficient update scheme with low complexity are proposed. Experiments carried on PAs show that the proposed model achieves similar linearization performance as other conventional models. Simultaneously, the proposed model has fewer coefficients and a reduction in the coefficient update of at least 50%. [ABSTRACT FROM AUTHOR]

This paper intensely studies the impact of the input nonlinearity caused by the transistor's feedback on the hybrid continuous class‐F power amplifier. The research extends the influence of input harmonics on class‐F power amplifiers to a more general form. Through waveform engineering, the impact of feedback is analyzed. By analyzing the change in cutoff angle caused by input nonlinearity, the change of the drain voltage and current waveforms of the hybrid continuous class‐F power amplifier can be obtained. The new drain voltage and current waveforms obtained from the analysis redefine the design space of source impedance and load impedance for the hybrid continuous class‐F power amplifier. By designing the corresponding input and output matching network, the second harmonic is suppressed, and finally, the hybrid continuous class‐F power amplifier achieves a high‐efficiency state. The research reveals that input harmonics also play an essential role in the design process of power amplifiers. A comparative experiment is designed to verify the theory. Simultaneously, a 1.6–2.8 GHz broadband hybrid continuous class‐F power amplifier is designed using this theory, with a saturation efficiency of more than 61.2% and a saturation power of more than 40.4 dBm. [ABSTRACT FROM AUTHOR]

An under-sampling digital predistortion based on a multi-tone mixing feedback technique (MTM-DPD) is presented in this article. In contrast to the under-sampling digital predistortion (DPD) based on conventional receivers, the proposed method could simultaneously reduce the sampling rate and acquisition bandwidth using a multi-tone mixing (MTM)-based feedback channel. The MTM-DPD is implemented with an evolved direct learning architecture, where the coefficients of a predistorter are estimated based on the aliased feedback signal, preprocessed input signal, and preprocessed kernels of the DPD model. To preprocess the input signal and kernels, the behavioral model of the MTM-based feedback channel and its corresponding identification algorithm are analyzed in detailed. Experimental results show that for a gallium nitride (GaN)-based power amplifier (PA) with 40-MHz input, under the excitation of a 17 tone LO signal with frequency interval 7.68 MHz, the MTM-DPD with sampling rate 15.36 MSPS and acquisition bandwidth 15.36 MHz could improve the adjacent channel power ratio (ACPR) from −30.1 to −46.5 dBc and the error vector magnitude (EVM) from 9.13% to 1.76%. Compared with the conventional full sampling DPD (FS-DPD), the MTM-DPD could reduce the cost of analog-to-digital converters (ADCs) in feedback channel significantly while maintaining satisfactory linearization performance. [ABSTRACT FROM AUTHOR]

In this article, a design method for a tri‐band power amplifier (PA) with dynamic drain bias voltage is presented. Continuous operation modes are used to expand the impedance design space. In the input and output matching networks, harmonic control circuits are set up to improve efficiency. The load harmonic impedances are obtained by continuous theory. Bias network and harmonic short circuit are used in the input matching network to control harmonics and obtain stop‐band. Dynamic drain bias enables the PA to adapt to different emission environments. With input and output harmonic control technology, a 0.9, 1.5, and 2.1 GHz GaN PA is designed to achieve high efficiency in different modes. The measured efficiencies of the fabricated PA at all three bands are more than 58.6%. At 1.5 GHz, when driven with a 20 MHz LTE signal with a 7 dB peak‐to‐average power ratio, by applying digital pre‐distortion, the PA prototype maintains an adjacent channel power ratio of better than −48.7 dBc. [ABSTRACT FROM AUTHOR]