The Realisation of Sampled Data Filters in Bipolar Technology

Advances in the integration of signal processing systems often depend on incorporating filter functions. These are so diverse that no single technique covers all the requirements. Thus there are cases where active RC filters of some sort are appropriate and others where digital filtering is necessary. There remains a large body of applications for which integrated RC filters, even with automatic tuning, are insufficiently precise and for which the overhead of A-D and D-A conversion is excessive, or the frequency too high, for DSP. Switched capacitor filters can often provide the necessary precision with reasonable complexity, but are usually considered only for low frequencies, and realised only in MOS technology. In this paper we discuss means of building similar filters in bipolar technology particularly in the video frequency band. Since the structures we developed differ from conventional switched capacitor filters we use the term "sampled data filters"