A CMOS transconductance amplifier architecture with wide tuningrange for very low frequency applications

摘要

A pseudodifferential CMOS operational transconductance amplifiern(OTA) with wide tuning range and large input voltage swing has beenndesigned for very small GM's (of the order of a fewnnanoamperes per volt). The OTA is based on a modified four-quadrantnmultiplier architecture with current division. A common-mode feedbackncircuit structure has been proposed and designed using floating-gatentransistors to handle large differential signals. Large on-chipncapacitors are emulated through impedance scaling circuits. Thencircuits, fabricated in a 1.2-Μm CMOS process, have been used tondesign a fourth-order bandpass filter and a relaxation oscillator.nExperimental results are in good agreement with the theoretical results