Analysis and Design of CMOS Radio-Frequency Power Amplifiers

The continuous advancement of semiconductor technologies, especially CMOS technology, has enabled exponential growth of the wireless communication industry. This explosive growth in turn has completely changed people’s lives. The CMOS feature size scale down greatly benefits digital logic integrations, which result in more powerful, versatile, and economical digital signal processing. Further research and development has pushed analog, mixed-signal, and even radio-frequency (RF) circuit blocks to be implemented and integrated in CMOS. Future generations of wireless communication call for even further level of integration, and as of now, the only circuit block that is rarely integrated in CMOS along with other parts of the system is the power amplifier (PA). Due to the fact that the PA in a wireless communication system is the most power-hungry circuit block, the integration of RF PA in CMOS would potentially not only save the cost of the wireless communication system real estate, but also reduce power consumption since die-to-die connection loss can be eliminated. RF PA design involves handling large amounts of voltage and current at the radio frequencies, which in the present wireless communication standards are in the range of giga-hertz. Therefore, a good understanding of many aspects related to RF PA design is necessary. Theoretical analysis of the communication system, nonlinear effects of the PA, as well as the impedance matching network is systematically presented. The analysis of the nonlinear effects proposes a formal mathematical description of the multitone nonlinearity, and through its relationship with two-tone test, the proposed PA design methodology would greatly reduce the design time while improving the design accuracy. A thorough analysis of the available architecture and design techniques for efficiency and linearity enhancement of RF PA shows that despite tremendous amounts of research and development into this topic, the fundamental tradeoff between the two still limits the RF PA implementation largely within SiGe, GaAs, and InP technologies. A RF PA for Wideband Code-Division Multiple Access (WCDMA) application standard is proposed, designed, and implemented in CMOS that demonstrates the proposed segmentation technique that resolved the main tradeoff between power efficiency and linearity. The innovative architecture developed in this work is not limited to applications in the WCDMA communication protocol or the CMOS technology, although CMOS implementation would take advantage of the readily available digital resources

The lumped reactions generated for deoxynucleoside triphosphate dTTP.

<p>The lumped reactions generated for deoxynucleoside triphosphate dTTP.</p

Synthesis of histidine from ribose-5-phosphate.

<p>The orange reactions are part of the linear synthesis route in the databases. The orange and purple metabolites are the <i>non-core</i> metabolites in the subnetwork. Purple reactions are balancing the non-core metabolites along the linear synthesis route. The subnetwork cannot produce any histidine from <i>core</i> network without including the purple reactions due to mass balance constraints. ‘non-core linear’ represents non-core metabolites along the linear synthesis pathway, ‘non-core mass balance’ represents the metabolite that appears as non-core within the purple reactions.</p

Inputs and outputs for lumpGEM.

<p>By defining the <i>core</i> precursors (AKG: alpha-keto glutarate, oxaloacetate, …), cofactor pairs (NADH, ATP, …), inorganics (SO₄, NH₄), biomass building blocks (<i>BBBs</i>), and <i>non-core</i> parts of metabolism, the GEM is provided to lumpGEM. The output of lumpGEM is thermodynamically feasible subnetworks, which with the <i>core</i>, is capable of synthesizing <i>BBBs</i>. The MILP characteristic of lumpGEM allows the building of alternative subnetworks and lumped reactions for the same <i>BBB</i>_<i>j</i>, and it ranks them according to yield.</p

Lumped reactions and statistics for amino acids.

<p>Lumped reactions and statistics for amino acids.</p

Lumped reactions for amino acids in <i>S</i>. <i>cerevisiae</i> using the core defined in the main text and comparison with <i>E</i>. <i>coli</i> lumped reactions.

<p>Lumped reactions for amino acids in <i>S</i>. <i>cerevisiae</i> using the core defined in the main text and comparison with <i>E</i>. <i>coli</i> lumped reactions.</p

Toward a Simple Predictive Molecular Thermodynamic Model for Bulk Phases and Interfaces

A simple molecular thermodynamic model, based on the QSPR/LSER approach, is presented. The development involves a critical examination of the suitability of available LSER molecular descriptors for calculations of properties of pure-component bulk phases, concentrated solutions, and interfaces. The appropriate descriptors for these calculations are obtained by applying simple and straightforward criteria on freely available data for pure compounds. These criteria arise from a re-examination of basic elements of the solvation picture on which the LSER approach resides. Extensive tables with molecular descriptors are reported. The predictive capacity of the model is tested against a variety of experimental data for mixtures including vapor–liquid equilibria, drug solubilities, and wetting behavior of solid polymer surfaces. Emphasis is given on hydrogen-bonded mixtures. The results are rather satisfactory, in view of the breadth of applications and the nonuse of adjustable parameters. All working equations are expressed in terms of LSER descriptors. The strength and weakness of the model are also critically discussed along with the perspectives of this unified approach to mixture thermodynamics

redGEM uses as inputs a GEM and the part of the metabolism of interest, along with the defined medium.

<p>With a 3 steps procedure that uses a set of methods, it generates core models for different purposes, such as FBA, TFA, kinetic modelling and metabolic flux analysis (MFA).</p

Metabolites that connect subsystems and the number of pairwise connections they achieve with different degrees of connection parameter <i>D</i>. (According to postulate 1, see Material and Methods).

<p>Metabolites that connect subsystems and the number of pairwise connections they achieve with different degrees of connection parameter <i>D</i>. (According to postulate 1, see <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1005444#sec009" target="_blank">Material and Methods</a>).</p

The specific growth rates (/hr) with 10 mmol/gDWhr uptake for each carbon source.

<p>The specific growth rates (/hr) with 10 mmol/gDWhr uptake for each carbon source.</p