arXiv subjects

J. L. González

Publications and source records attributed to J. L. González.

5 recordsLinked to original sources

arXiv2025

Impact of Passive Element Technological Limits on CMOS Low-Noise Amplifier Design

This paper investigates the impact of technological constraints on passive elements in the design of inductively degenerated CMOS low-noise amplifiers (LNAs). A theoretical analysis is combined with circuit simulations in a 130-nm CMOS process at 2.45~GHz to explore how the available inductance and capacitance values limit key design objectives such as maximum gain, minimum power consumption, and transistor sizing. Results show that these limits significantly restrict the achievable design space, particularly for low-power implementations, and highlight the need to incorporate detailed passive-element models into RF integrated circuit design flows.

eess.SY↗

arXiv2025

A Proposal for Yield Improvement with Power Tradeoffs in CMOS LNAs (English Version)

This paper studies an architecture with digitally controllable gain and power consumption to mitigate the impact of process variations on CMOS low-noise amplifiers (LNAs). A \SI{130}{nm}, \SI{1.2}{V} LNA implementing the proposed architecture is designed based on an analysis of variability in traditional LNAs under different bias currents and on the corresponding effects on the performance of a complete receiver. Two different adjustment strategies are evaluated, both of which are compatible with previously reported built-in self-test (BIST) circuits. Results show that the proposed architecture enables yield enhancement while keeping low-power operation compared with traditional LNAs.

eess.SY↗

arXiv2004

Theory of the Diamagnetism Above the Critical Temperature for Cuprates

Recently experiments on high critical temperature superconductors has shown that the doping levels and the superconducting gap are usually not uniform properties but strongly dependent on their positions inside a given sample. Local superconducting regions develop at the pseudogap temperature ($T^*$) and upon cooling, grow continuously. As one of the consequences a large diamagnetic signal above the critical temperature ($T_c$) has been measured by different groups. Here we apply a critical-state model for the magnetic response to the local superconducting domains between $T^*$ and $T_c$ and show that the resulting diamagnetic signal is in agreement with the experimental results.

cond-mat.supr-con↗

arXiv2004

Upper critical field $H_{c2}$ calculations for the high critical temperature superconductors considering inhomogeneities

We perform calculations to obtain the $H_{c2}$ curve of high temperature superconductors (HTSC). We consider explicitly the fact that the HTSC possess intrinsic inhomogeneities by taking into account a non uniform charge density $ρ(r)$. The transition to a coherent superconducting phase at a critical temperature $T_c$ corresponds to a percolation threshold among different superconducting regions, each one characterized by a given $T_c(ρ(r))$. Within this model we calculate the upper critical field $H_{c2}$ by means of an average linearized Ginzburg-Landau (GL) equation to take into account the distribution of local superconducting temperatures $T_c(ρ(r))$. This approach explains some of the anomalies associated with $H_{c2}$ and why several properties like the Meissner and Nernst effects are detected at temperatures much higher than $T_c$.

cond-mat.supr-con↗

arXiv2003

Is the Superconductiong State for the Cuprates Reached Through a Percolation Transition?

Several recent experiments have revealed that the charge density $ρ$ in a given compound (mostly underdoped) is intrinsic inhomogeneous with large nanoscale spatial variations. Therefore it is appropriate to define a local charge density $ρ(r)$. These differences in the local charge concentration yield insulator and metallic regions, either in an intrinsic granular or in a stripe morphology. In the metallic region, the inhomogeneous charge density produces spatial or local distributions of superconducting critical temperatures $T_c(r)$ and zero temperature gap $Δ_0(r)$. We propose that the superconducting phase in high-$T_c$ oxides is reached when the temperature reachs a value which superconduction regions with different critical temperatures percolates. We show also that this novel approach is able to reproduce the phase diagram for a family of cuprates and provides new insights on several experimental features of high-$T_c$ oxides

cond-mat.supr-con↗