By Andre van Bezooijen, Reza Mahmoudi, Arthur H.M. van Roermund
The RF front-end – antenna mixture is an important a part of a cell phone simply because its functionality is especially proper to the hyperlink caliber among hand-set and mobile community base-stations. The RF front-end functionality suffers from adjustments in working atmosphere, like hand-effects, which are frequently unpredictable.
Adaptive RF Front-Ends for handheld Applications provides an research at the influence of fluctuating environmental parameters. with a view to conquer undesired habit diversified adaptive keep an eye on equipment are handled that make RF frond-ends extra resilient: adaptive impedance keep watch over, and adaptive energy control.
Several adaptive impedance keep watch over thoughts are mentioned, utilizing a priori wisdom on matching community homes, so as to simplify strong 2-dimensional keep watch over. A known safeguard thought is gifted, in accordance with adaptive strength keep an eye on, 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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Extra info for Adaptive RF Front-Ends for Hand-held Applications
In case of adaptive impedance matching, treated in Chapter 3, small variations in component values can result in large variations of the matching impedance,1 especially for high-order matching networks that need to tune over a wide load impedance and frequency range. Especially the accuracy of RF-MEMS capacitors is rather limited, due to variations in dielectric layer thickness, roughness, plate and spring bending, etc. In addition, parasitic capacitors and inductors of the components and that of interconnect usually have a large impact on the impedance transformation.
6 visualizes control of f(x) to R by stepping the independent variable x according to the Sign of error either to xA or to xMIN. Now proper convergence to a desired solution A is achieved for xB < x < XMAX, which extends beyond the monotone region of f(x). For x < XB the system diverges to a boundary given by XMIN. The impedance region of robust control is determined by matching network control properties and the chosen control algorithm. This region of robust control can be visualized as the overlapping area between the impedance tuning region of the network and the region of convergence of the algorithm, as shown in Fig.
7 Visualization of the die temperature TDIE as a function of the phase of gamma for VSWR1 ¼ 1, 2, 3, and 4. 8 shows the die temperature as a function of mismatch. 24), the efficiency has a maximum for a mismatch phase of zero degrees, and increases with increasing VSWR. The amplifier efficiency is inverse proportional the supply voltage. 1. 24 2 Adaptive RF Front-Ends 40 4 30 Eff [%] 3 20 2 1 10 0 –180 –90 0 90 PhaseOfGamma_1 [degrees] 180 Fig. 8 Visualization of the efficiency as a function of the phase of gamma for VSWR1 ¼ 1, 2, 3, and 4.