By Andre van Bezooijen, Reza Mahmoudi, Arthur H.M. van Roermund
The RF front-end – antenna blend is a crucial a part of a cellphone simply because its functionality is particularly correct to the hyperlink caliber among hand-set and mobile community base-stations. The RF front-end functionality suffers from alterations in working surroundings, like hand-effects, which are usually unpredictable.
Adaptive RF Front-Ends for handheld Applications offers an research at the impression of fluctuating environmental parameters. with a view to triumph over undesired habit varied adaptive keep watch over tools are handled that make RF frond-ends extra resilient: adaptive impedance keep watch over, and adaptive strength control.
Several adaptive impedance keep an eye on options are mentioned, utilizing a priori wisdom on matching community houses, on the way to simplify strong 2-dimensional regulate. A widely used safety thought is gifted, according to adaptive energy keep watch over, which improves the ruggedness of an influence amplifier or preserves its linearity below 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
Both capacitors are tuned from 1 to 10 pF and the inductor from 4 to 12 nH, while f ¼ 900 MHz. Crossing lines indicate that multiple C1–C2–L combinations provide the same impedance transformation. 5). In addition, solutions that result in component values close to the boundary of their tuning range might get out of range due to load impedance variations. 1 Introduction 41 L Many C1 C2 L values give same ZM For a fixed L, two C1 C2 combinations give same ZM C2 C1 Fig. 3 The next section treats some aspects of robust control.
5–2 dB) is significant compared to the noise figure of low noise amplifiers (LNA) (typically 2–3 dB) that are usually integrated in the TRx. Temperature drift of the blocking filter frequency characteristic can be critical for blocking filters, similar to that of duplex filters. Usually blocking filters are implemented in SAW or BAW technology, similar to that of duplex filters. 3 Fluctuations in Operating Conditions Cellular phones operate in strongly varying environments. Fluctuations in the operating conditions have strong impacts on link quality, talk-time, and ruggedness requirements of a phone.
2). 4 Impact of Variables 17 Fig. 2 Circuit diagram of a class-AB power amplifier using a bipolar transistor USUP ISUP UCOL ICOL ZLOAD PLOAD UIN PDISS UQ in which Io is the saturation current of the transistor and UT the thermal voltage. The base-emitter voltage consists of two terms: the DC bias voltage UQ, and a sinusoidal signal of excitation with an amplitude AIN. The exponential relationship can be approximated by a Taylor series and the magnitude of the harmonic components can be determined by applying a Fourier transformation .
Adaptive RF Front-Ends for Hand-held Applications by Andre van Bezooijen, Reza Mahmoudi, Arthur H.M. van Roermund