Title :
Robust highly linear high-frequency CMOS OTA with IM3 below - 70 dB at 26 MHz
Author :
Huang, Wenchang ; Sánchez-Sinencio, Edgar
Author_Institution :
Dept. of Electr. Eng., Texas A&M Univ., College Station, TX, USA
fDate :
7/1/2006 12:00:00 AM
Abstract :
An enhanced configuration for a linearized MOS operational transconductance amplifier (OTA) is proposed. The proposed fully differential OTA circuit is based on resistive source degeneration and an improved adaptive biasing technique. It is robust to process variation, which has not been fully shown in previously reported linearization techniques. Detailed harmonic distortion analysis demonstrating the robustness of the proposed OTA is introduced. The transconductance gain is tunable from 160 to 340 μS with a third-order intermodulation (IM3) below -70 dB at 26 MHz. As an application, a 26-MHz second-order low-pass filter fabricated in TSMC 0.35-μm CMOS technology with a power supply of 3.3 V is presented. The measured IM3 with an input voltage of 1.4 Vpp is below - 65 dB for the entire filter pass-band, and the input referred noise density is 156nV/√Hz. The cutoff frequency of the filter is tunable in the range of 13-26 MHz. Theoretical and experimental results are in good agreement.
Keywords :
CMOS analogue integrated circuits; continuous time filters; differential amplifiers; linearisation techniques; operational amplifiers; 0.35 micron; 1.4 V; 13 to 26 MHz; 160 to 340 mus; 26 MHz; 3.3 V; CMOS operational transconductance amplifier; IM3; adaptive biasing; continuous-time filters; cutoff frequency; fully differential OTA circuit; harmonic distortion analysis; linearization techniques; linearized MOS OTA; noise density; second-order low-pass filter; third-order intermodulation; transconductance gain; CMOS technology; Harmonic analysis; Harmonic distortion; Linearization techniques; Low pass filters; Operational amplifiers; Power harmonic filters; Robustness; Transconductance; Tunable circuits and devices; Linearized operational transconductance amplifier (OTA); MOS transconductors; OTA-C filter; Volterra series; continuous-time filters; harmonic distortion;
Journal_Title :
Circuits and Systems I: Regular Papers, IEEE Transactions on
DOI :
10.1109/TCSI.2006.875187