Artículos regulares

 

Procesamiento analógico a partir de elementos altamente resistivos

 

Analog Processing based on Quasi-Infinite Resistors

 

Carlos Muñiz-Montero¹, Luis Abraham Sánchez-Gaspariano¹, Víctor Hugo Ponce-Ponce², María Elena Aguilar-Jáuregui² y Osvaldo Espinosa-Sosa²

 

¹ Universidad Politécnica de Puebla, México. carlosmm2k@gmail.com, luisabraham.sg@gmail.com

² Centro de Investigación en Computación, Instituto Politécnico Nacional, DF, México. vponce@cic.ipn.mx, maguilar@cic.ipn.mx, espinosa@cic.ipn.mx

 

Artículo recibido el 30/11/2010
Aceptado el 16/01/2013

 

Resumen

El presente trabajo propone una técnica para diseñar, a partir de elementos altamente resistivos, circuitos integrados CMOS analógicos tales como amplificadores compensados en offset, filtros sintonizables de baja frecuencia, espejos de corriente programables y generadores de funciones de membresía. La técnica propuesta incorpora transistores operando en la región de inversión débil para reducir los requerimientos de área y las contribuciones de offset, así como para reducir las componentes de ruido y distorsión, mejorando el compromiso exactitud-velocidad-potencia. Éstas características permiten facilitar el acondicionamiento de señales de baja frecuencia y habilitar el diseño de dispositivos con sintonización multidécada de ganancia y frecuencia. Por otro lado, los circuitos propuestos son atractivos para la implementación analógica de arquitecturas reservadas al ámbito digital, tales como filtros adaptables y sistemas difusos, por mencionar algunos, así como dispositivos de procesamiento y acondicionamiento de señal de alta eficiencia. Se reportan caracterizaciones a partir de simulaciones, mediciones y análisis estadísticos de prototipos diseñados con una tecnología CMOS de 0.5|im de largo de canal, dos capas de polisilicio y tres capas de metal. Los resultados obtenidos concuerdan con aquellos anticipados en el diseño de los circuitos.

Palabras clave: CMOS, amplificadores, filtros, lógica difusa, elementos altamente resistivos.

 

Abstract

This work proposes a technique for design of CMOS analog integrated circuits such as offset compensated amplifiers, low-frequency filters, programmable current mirrors and membership function generators, based on high-value (quasi-infinite) resistors. The proposed technique incorporates transistors operating in weak-inversion mode in order to reduce the area requirements and minimize the DC-offset. In addition, improvement on both, noise performance and linearity, are achieved along with an enhanced speed-accuracy-power tradeoff. Those features make easier the processing of low-frequency signals and allow the design of systems with multi-decade tunability of gain and frequency. The presented circuits are attractive for implementation of high-accuracy processors for signal conditioning as well as architectures usually reserved to digital approaches, for instance neural networks, adaptive filters, and neuro-fuzzy systems, to mention a few. Characterization through computer simulations, statistical analysis and experimental measurements of prototypes in a double-poly, three metal layers, 0.5pm CMOS technology are reported. The attained results follow the course anticipated in the design of the circuits.

Keywords: CMOS, amplifiers, filters, fuzzy logic, quasiinfinite resistors.

 

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Agradecimientos

Este trabajo ha sido soportado parcialmente por el proyecto 181201 del Consejo Nacional de Ciencia y Tecnología (CONACyT), por el proyecto UPPUE-PTC-047 del Programa de Mejoramiento del Profesorado (PROMEP) y por el proyecto PICCT08-22 del convenio IPN-Instituto de Ciencia y Tecnología del Distrito Federal (ICYTDF).

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