Linearity improvement technique for CMOS continuous-time filters

A linearity improvement technique using a combination of passive resistors and current-steering MOS transistors as a variable resistance element is applied in the implementation of low-distortion continuous-time filters in complementary metal-oxide-semiconductor (CMOS) technology. This work is motivated by the fact that to date, most of the techniques in continuous-time, electronically tunable filters perform quite poorly in linearity. The proposed technique relies on the linearity of the passive resistors and the tunability of the current-steering MOS transistors operating in the triode region. By novel application of systematic feedback loops and by placing the nonlinear elements inside the feedback, the distortion resulting from the nonlinear devices is greatly reduced by the filter loop gain. Theoretical and experimental results, in agreement, show a significant improvement in linearity. For an audio-band (22-kHz) fifth-order Bessel filter implementation, linearity better than $-$90 dB THD is demonstrated given a 2 kHz, 4 $V\sb{p-p}$ signal in a 5-V system. The filter implementation includes a simple and novel automatic frequency-tuning method, which employs a switched-capacitor reference resistor instead of applying a conventional phase-locked loop technique or its variations. Also included in the filter implementation is a linear programming approach to optimize the dynamic range, under the constraint of a fixed capacitor area that is assumed to be the dominant factor in the total chip area.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Moon, Un-Ku

Contributors dc:contributor

• Song, Bang-Sup

• Engineering, Electronics and Electrical
• Physics, Electricity and Magnetism
• Physics, Condensed Matter

Statement dc:rights

• Copyright 1994 Moon, Un-Ku

Language dc:language

eng

Identifier

AAI9503275
(UMI)AAI9503275

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/23151