Active-RC Filters Using the Gm-Assisted OTA-RC Technique

Author

Thyagarajan, Siva V. ; Pavan, Shanthi ; Sankar, Prabu

Author_Institution

Dept. of Electr. Eng., Indian Inst. of Technol., Madras, Chennai, India

Volume

46

Issue

7

fYear

2011

fDate

7/1/2011 12:00:00 AM

Firstpage

1522

Lastpage

1533

Abstract

The linearity of conventional active-RC filters is limited by the operational transconductance amplifiers (OTAs) used in the integrators. Transconductance-capacitance (Gm-C) filters are fast and can be linear- however, they are sensitive to parasitic capacitances. We explore the Gm-assisted OTA-RC technique, which is a way of combining Gm-C and active-RC integrators in a manner that enhances the linearity and speed of the latter, while adding negligible extra noise or power dissipation. Measurements from a fifth-order Chebyshev filter with 20 MHz bandwidth, designed in a 0.18 μ m CMOS process, demonstrate the efficacy of Gm-assistance in an active-RC integrator.

Keywords

CMOS analogue integrated circuits; Chebyshev filters; RC circuits; active filters; integrating circuits; operational amplifiers; CMOS process; Gm assisted OTA-RC technique; active RC filter; active RC integrator; bandwidth 20 MHz; fifth order Chebyshev filter; operational transconductance amplifier; parasitic capacitance; size 0.18 mum; transconductance capacitance filter; Linearity; Noise; Nonlinear distortion; Resistance; Resistors; Stability analysis; Transconductance; Active-RC filter; Gm-OTA-C; assisted opamp; channel selection; folded cascode; gm-C filter; intermodulation distortion; linear filter; linearization; operational amplifier; operational transconductance amplifier (OTA); resistor servo; triode mode transconductor; tuning;

fLanguage

English

Journal_Title

Solid-State Circuits, IEEE Journal of

Publisher

ieee

ISSN

0018-9200

Type

jour

DOI

10.1109/JSSC.2011.2143590

Filename

5765707