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This paper describes a new type of power amplifier (PA) module with a predistortion function and can be applied to N-CDMA (narrow-band CDMA system defined in IS-95B Standard) handset terminals. Distortion compensation technology to improve the efficiency of the PA is discussed quantitatively. Various parameters to be considered in designing are investigated in detail. The predistortion technology proposed is based on the lookup-table method using the input and output signal envelopes and can operate independently from the baseband block. By omitting adaptative predistortion for amplitude/phase modulation and integrating the main controlling functions on a single CMOS integrated-circuit chip, predistortion capability has been realized in a PA module. The PA module has power-added efficiency (PAE) of 48% at an output power of 27.5 dBm. This PAE is very high in comparison with that of the conventional PA module for N-CDMA. Index Terms--Amplitude-amplitude modulation (AM/AM), amplitude-phase modulation (AM/PM), code division multiple access (CDMA), module, power-added efficiency (PAE), power amplifier (PA), predistortion.

A CMOS architecture for a floating linear resistor which exploits the square-law model of the MOS transistor is presented. The architecture is Programmable by dc control voltage and is easily modified such that it is threshold-voltage independent, allowing large signal handling and immunity to substrate noise. Design trade-offs and device size optimization are investigated. Second-order effects due to mobility degradation and channel length modulation are analyzed and a simple high frequency model for the resistor is developed. The architecture is fabricated in a 210 [mu]m p-well CMOS MOSIS process. The resistor occupies 210 [mu]m x 270 [mu]m consumes .4-4 mW with [+ or -]5 V supply and exhibits a signal (at 1% THD) to noise ratio of more than 100 dB over a 1-V range of the dc control voltage., A complementary metal oxide semiconductor (CMOS) implementation of a floating one-port linear resistor is presented. A discussion of the proposed architecture, which is based on the MOS transistor square-law model, includes an evaluation of second-order effects, design trade-offs and steps for device optimization. A model for the resistor's behavior at high frequency operation is provided together with results from a prototype fabricated in a two-micrometer CMOS technology are also given.

The formation of distinct supramolecular assemblies, including a metastable species, is revealed for a lipophilic guanosine (G) derivative in solution and in the solid state. Structurally different G-quartet-based assemblies are formed in chloroform depending on the nature of the cation, anion and the salt concentration, as characterized by circular dichroism and time course diffusion-ordered NMR spectroscopy data. Intriguingly, even the presence of potassium ions that stabilize G-quartets in chloroform was insufficient to exclusively retain such assemblies in the solid state, leading to the formation of mixed quartet and ribbon-like assemblies as revealed by fast magic-angle spinning (MAS) NMR spectroscopy. Distinct N−H⋅⋅⋅N and N−H⋅⋅⋅O intermolecular hydrogen bonding interactions drive quartet and ribbon-like self-assembly resulting in markedly different 2D 1H solid-state NMR spectra, thus facilitating a direct identification of mixed assemblies. A dissolution NMR experiment confirmed that the quartet and ribbon interconversion is reversible-further demonstrating the changes that occur in the self-assembly process of a lipophilic nucleoside upon a solid-state to solution-state transition and vice versa. A systematic study for complexation with different cations (K+, Sr2+) and anions (picrate, ethanoate and iodide) emphasizes that the existence of a stable solution or solid-state structure may not reflect the stability of the same supramolecular entity in another phase. [ABSTRACT FROM AUTHOR]