This paper proposes an improved estimation approach for modelling RF power amplifiers (PAs) using the Saleh behavioural model. The proposed approach is appropriate for solid-state PA technologies. The 1-dB compression point of the PA is included in the estimation approach to improve the estimation of the Saleh coefficients. Thus, expressions are derived to describe the relationship between the parameters of the Saleh model and the manufacturing specifications of PAs: gain (G), third-order intercept point (IP(3)) and 1-dB compression point (P(1dB)). This method is a simple estimation of a memoryless amplitude-to-amplitude (AM/AM) nonlinearity to benefit RF designers evaluating the PA distortion using the PA parameters: P(1dB), G, and IP(3), before conducting experimental validation. The linearisation method using digital predistortion (DPD) is derived as a function of G, IP(3), and P(1dB), for mitigating the AM/AM nonlinear distortion. Finally, the modelling and DPD techniques are both evaluated using the experimental results of the GaAs PA.

In this article, a novel method to design broadband linear power amplifier (BL‐PA) is presented. By adding the image parts for harmonics and intermodulation products (HIMPs), a suboptimal solution of efficiency and linearity in continuous frequencies can be achieved at a broadband to improve the efficiency and linearity performance of the BL‐PA. For verification, a BL‐PA operating 3.2‐3.8GHz is designed and the performances are assessed in multi modes.

Cell free (CF) massive multiple input multiple output (mMIMO) has been suggested as a key solution to meet the high data rate demands of future wireless communications. Studying the performance of these systems in practical scenarios such as in the presence of hardware impairments is of vital importance. In this paper, we study the effect of solid state power amplifier non-linearity on the uplink and downlink sum-rate of CF mMIMO systems. We derive closed form expressions for the uplink and downlink achievable sum-rates of orthogonal frequency division multiplexing (OFDM) based CF mMIMO systems. Our results show that in the uplink the sum-rate does not increase unlimitedly as the number of access points (AP) increases, being upper bounded, contrarily to the ideal linear case. In fact, the rate of each user is limited by the distortion signal of its power amplifier. However, in the downlink, the sum-rate of the system with non-linear power amplifiers is not bounded and increases unlimitedly with the number of APs. Our results also indicate that for the same signal to distortion ratio (SDR) at the power amplifier output or the same normalized saturation level of the power amplifiers, the relative downlink sum-rate degradation is lower than the relative uplink sum-rate degradation (both with respect to their corresponding values in the ideal linear case). In fact, our results confirm that the user side power amplifier non-linearity has higher impact on the system performance than the power amplifier non-linearity on the AP antennas.

5th generation systems (5G) will be based on Orthogonal Frequency Division Multiplexing (OFDM) multicarrier modulation technique. This modulation has a very high Peak to Average Power Ratio (PAPR). This high PAPR is a drawback when nonlinear Power Amplifiers (PA) are operated near the saturation region, for energy efficiency purposes, due to in-band and out-of-band impairments. In this paper, a new PAPR reduction technique called Iterative Dichotomy PAPR (IDP) is proposed. This method is suited for any multicarrier modulation and is studied here using realistic PA model. For evaluating the signal distortions, two main metrics have been considered to evaluate the performance of IDP technique: bit error rate (BER) and power spectrum density (PSD). The analytical expressions of the IDP technique for any dichotomy order M is firstly described and subsequently the energy efficiency for different M values is compared. We have shown that the proposed IDP method reduces the PAPR by 2.2dB for M = 2 and 4dB for M = 4. Regarding the energy efficiency, for the same Error Vector Magnitude (EVM) and the same PA power consumption, the output signal power obtained with the IDP based technique outperforms classical OFDM by 20%, 50% and 80% for M = 2, M = 3 and M = 4, respectively.

This paper revises the efficiency optimization equations for magnetic-transformer-based power combiner/divider impedance transformation networks (e.g., distributed active transformer). It evaluates their usability for high millimeter-wave frequencies, where the distributed behavior of a transformer and its loss become relevant. As is demonstrated, the standard optimization equations do not lead to an optimum result. To enable the optimization of distributed transformers, an extended lumped equivalent circuit model is proposed and used for the derivation of new optimization equations. The novel equations enable the design of magnetic transformers with maximum efficiency. To demonstrate the performance that can be achieved with optimized distributed magnetic transformer networks at millimeter-wave frequencies, measurement results of an R-band (i.e., 170-260 GHz)/H-band (i.e., 220-325 GHz) radio frequency power amplifier (PA) are presented. With an output power of approximately 6.2 dBm at 260 GHz, the amplifier is among the state of the art for mHEMT PAs operating in this frequency range. With its relative 3-dB bandwidth of 29%, however, it surpasses all those reported mHEMT PAs to date.

Speakers are quite remarkable in their ability to convert electrical audio signals into sound waves for our listening pleasure (or displeasure). Speakers of all sizes, from built-in smartphones to live sound subwoofers, require amplifiers.

In addition there are several stages of IF amplifiers, which is just a lower frequency of RF. Overall, we need to increase the few microvolts up to several volts. That’s a voltage gain of about 1 million.

A novel design space of load modulated (LM) inverse Class‐F high power amplifiers (PAs) with extended conduction angle is proposed. The effects of the driven level factor β and the biasing operation factor ρ on the third‐harmonic generation are discussed. The harmonic generation mechanism shows that the knee voltage effects are the source of third‐harmonics for LM inverse Class‐F PAs. The definition of the inverse Class‐F mode is consistently valid under the circumstance of load modulation in a limited output power back‐off (OPBO) range. Meanwhile, the conduction angle θ0 can be extended from π/2 to a limited value (<110°) to keep the standard waveforms of inverse Class‐F mode and maintain high efficiency. After introducing the “continuous concept” and the second harmonic manipulation method, the mathematical design space of inverse Class‐F PAs with extended conduction angle is derived. Calculation shows that the purely conductive load modulation can enable high back‐off efficiency operation for LM inverse Class‐F PAs. As proof of concept, a demonstrator amplifier is fabricated and measured. The experimental results show that the power added efficiency (PAE) with optimum Vctrl is improved by 5% over an OPBO range of 6 dB compared with the same PA with fixed Vctrl.