Design of DC-stable log-domain filters and their application in multistandard receivers

A study of the concepts involved in the bias-stability of log-domain filters is presented. Through a thorough analysis of the factors contributing to the existence of multiple and unstable operating points in log-domain filters, a biquad architecture that overcomes these drawbacks is proposed. This is accompanied with a theoretical verification of both stability and the input-output linear behavior. The study provides a foundation for the design and implementation of other bias-stable log-domain circuits.; This thesis also presents the design of a multistandard channel-select filter for GSM, IS-95, and WCDMA. The filter's tunability extends from 100 kHz to 20.05 MHz. The implemented 6th-order quasi-Butterworth log-domain filter was fabricated in a Silicon Germanium (SiGeHP5) technology, operates from a supply voltage as low as 1.2 V, and consumes a maximum power of 12.9 mW at 20.05 MHz cutoff frequency. Dynamic biasing techniques are employed in order to extend the SFDR of the filter, e.g. from SFDR = 39 dBm to SFDR = 48 dBm at 20.05 MHz cutoff frequency.