Active filter synthesis based on tuneable log-domain lossy integrators

A new technique for the design of tuneable log-domain all-pole and elliptic filters is described which is based on the use of a building block derived by using wave active filter principles. This block has been developed around a current mode tuneable log-domain lossy integrator. The same block is used throughout the structure of the derived circuits and hence simulated active filters of any order and type can be designed in a modular way. The derived circuits integrate the low-sensitivity nature of the prototype LC circuits and the log-domain potential for high-frequency operation, low distortion and extended dynamic range. In addition they are suitable for low-voltage design