A fully-programmable analog log-domain filter circuit

This paper describes the design of a general purpose continuous-time analog filter that utilizes log-domain integrator circuits. The coefficients of the filter are digitally programmable and externally controlled using a serial input data stream. Both the poles and the zeros of the filter are adjustable allowing arbitrary filter function implementation. The filter has been designed in a 0.8 micron BiCMOS technology for 3.0 volt operation and a maximum cut-off frequency of 75 MHz. The appropriate V-to-I and I-to-V converters are included for normal voltage operation.