Performance limitations in a programmable digitally tuned CMOS OTA-C second-order bandpass filter architecture. (Volumes I and II)

A digitally programmable digitally tuned analog filter architecture based on an analog continuous-time CMOS OTA-C (operational transconductance amplifier and capacitor) was developed and characterized with emphasis on the factors that inherently limit the performance of filters utilizing this architecture. This versatile architecture is tuned using a microprocessor, giving this architecture the capability of conducting in-field self tests and operating at high Qs and high frequencies. The filter architecture consists of three basic functional blocks: a controllable filter, a Performance Measurement System which characterizes the filter's performance, and a tuning algorithm which evaluates the filter's performance and appropriately adjusts the control parameters. Unlike the master/slave analog tuned filter structures, this architecture uses direct performance measurements as the basis for the tune which allow independence from matching analog components and the use of filters that do not behave ideally. Limitations of this architecture include that it is expensive since it is not monolithic and requires extensive support circuitry and that tuning times are lengthy.;The controllable filter is designed to give independent control of filter parameters for a 2...