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Radio frequency power amplifiers (RF PA) are widely used for several applications e.g. wireless communication, wireless power transmission (WPT) and radio frequency heating. In general, the choice of power amplifier's operating class is based on requirements regarding linearity and power efficiency. For applications in which linearity is not a critical issue whereas high efficiency is desired, switched-mode...
A new technique called Auxiliary Envelope Tracking (AET) is proposed, which demonstrates substantial improvement in linearity of RF power amplifiers. A small amplitude envelope-tracking voltage is superimposed on the fixed DC bias of a specially designed 25W GaN HEMT Class AB RF power amplifier (RFPA). A large improvement in third-order intermodulation (IM3) distortion has been observed while maintaining...
In this paper, a technique for extracting the Taylor series expansion coefficients of a varactor reactive nonlinearity is presented. A single diode and a dual-device antiseries (back-to-back cathode) combination have been characterized, aimed to accurately control their contribution to the residual intermodulation distortion (IMD) appearing in load-modulated power amplifiers (PAs). A test set-up for...
Low-frequency, baseband effects in Power Amplifiers can become particularly important when steps are taken to improve operational efficiency through the application of `envelope' based approaches such as Envelope Elimination and Restoration (EER) and Envelope Tracking (ET). The aim of this paper is to demonstrate how a broadband modulated time-domain measurement system, when used in combination with...
The estimation of 1 dB compression and third-order intercept points can be obtained after the cross-correlation between dynamic current and output voltage of radio frequency power amplifiers. Estimation is performed using power measures and not power inferred from voltage measures. The underlining theory and a correlator that allows implementing this measurement on-chip are presented. The trade-off...
This paper presents a rigorous way to quantify the role played by higher baseband impedances in determining baseband electrical memory effects observed in power transistors under two-carrier excitation. These effects typically appear not only as asymmetrical distortion terms in the frequency domain, but also more reliably as a recognizeable hysteresis or looping in the dynamic transfer characteristics...
In this paper, the results of dynamic load modulation on a high power amplifier is shown with experiments. A simple static nonlinear model is used as an inverse model, and by dynamically controlling both the input signal to the power amplifier and the load impedance, high efficiency operation of the power amplifier is achieved. The modulated measurements show the feasibility of dynamic load modulation...
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