A CMOS Transconductance Amplifier Architecture With Wide Tuning Range for Very Low Frequency Applications
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A pseudodifferential CMOS operational transconductance amplifier (OTA) with wide tuning range and large input voltage swing has been designed for very small G M's (of the order of a few nanoamperes per volt.) The OTA is based on a modified four-quadrant multiplier architecture with current division. A common-mode feedback circuit (CMFB) structure has been proposed and designed using floating-gate transistors to handle large differential signals. Large on-chip capacitors are emulated through impedance scaling circuits. The circuits, fabricated in a 1.2 μm CMOS process, have been used to design a fourth-order bandpass filter and a ralaxation oscillator. Experimental results are in good agreement with the theoretical results.
author list (cited authors)
Veeravalli, A., Sánchez-Sinencio, E., & Silva-Martínez, J.