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

Design Methodology for Common-Mode Stability of OTA-based Gyrators

This paper presents a design methodology for common-mode (CM) stability of operational transconductance amplifier (OTA)-based gyrators. The topology of gm−C active inductors is briefly reviewed. Subsequently, a comprehensive mathematical analysis on the CM stability of OTA-based gyrators is presented. Sufficient requirements for the gyrator’s CM stability, that easily can be considered during the design process of common-mode feedback (CMFB) amplifiers, are defined. Based on these stability requirements, a design methodology and a design procedure are proposed. Finally, in order to validate the proposed procedure, a resonator with 20 MHz resonance frequency and a quality factor of 20 is fabricated with UMC 180-nm CMOS technology and its CM stability is examined