Download Adaptive RF Front-Ends for Hand-held Applications by Andre van Bezooijen, Reza Mahmoudi, Arthur H.M. van Roermund PDF

By Andre van Bezooijen, Reza Mahmoudi, Arthur H.M. van Roermund

The RF front-end – antenna mix is an important a part of a cellphone simply because its functionality is particularly suitable to the hyperlink caliber among hand-set and mobile community base-stations. The RF front-end functionality suffers from adjustments in working setting, like hand-effects, which are frequently unpredictable.

Adaptive RF Front-Ends for handheld Applications provides an research at the effect of fluctuating environmental parameters. with a purpose to conquer undesired habit assorted adaptive regulate equipment are handled that make RF frond-ends extra resilient: adaptive impedance keep watch over, and adaptive strength control.

Several adaptive impedance keep watch over options are mentioned, utilizing a priori wisdom on matching community houses, with a view to simplify powerful 2-dimensional keep an eye on. A primary safeguard proposal is gifted, according to adaptive energy regulate, which improves the ruggedness of an influence amplifier or preserves its linearity lower than extremes. It includes over-voltage, over-temperature, and under-voltage protection.

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Sample text

Since insertion loss and bandwidth can not easily be detected, they can not easily be made part of control criteria unless elaborate network computation is applied. 12) This error is a function of the control inputs x setting the capacitor values of the network. The disturbance d represents, for instance, the difference between a nominal load impedance (typically 50 O) and the actual load impedance. Hence, d represents load mismatch and is an element of a domain D that defines the entire region of load impedances over which the cost function needs to be minimized.

The impact of these fluctuating conditions on the performance of a cellular phone and its RF front-end is visualized in Fig. 1 as a chain of causes and effects. The output power (A), power transistor load impedance (B), supply voltage (C), and ambient temperature (D) determine the collector (or drain) voltage (I) and current (III), and in relation to those, the dissipated power, efficiency and die temperature (II), which, on their turn, affects talk-time (1), link quality (2), and breakdown behavior of the power amplifier (3).

4 Impact of Variables In this section we present a mathematical analysis on the behavior of a bipolar class-AB power amplifier transistor under fluctuating operating conditions. The collector current, collector voltage, die temperature and amplifier efficiency are expressed as functions of the collector load impedance, supply voltage and ambient temperature. To simplify the analysis, feedback, saturation, self-heating, and frequency dependencies are ignored (Fig. 2). 4 Impact of Variables 17 Fig.

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