Design methodology for controlled-Q resonators in OTA-based filters

This paper presents a design methodology for high quality factor resonators based on operational transconductance amplifier (OTA) employed in active filters. The quality factor of a resonator, as its main specification, is translated to the requirements of the OTA. Moreover, the effects of the OTA´s finite output resistance and internal poles are investigated. The results provide a useful chart and a simple methodology to design a resonator with a desired quality factor. The design methodology has been validated by fabricating a resonator with 8 MHz resonance frequency and a quality factor of around 10 using UMC 180-nm CMOS technology.