Transmultiplexers with Either Analog Conversion Circuits, Wave Digital Filters, or SC Filters--A Review

Since more advanced transmultiplexer concepts have to compete with elementary alternative solutions derived from simple back-to-back connections, they have to aim at high efficiency and robust performance, the latter meaning that they should be quite insensitive against disturbances inherent to the type of technology adopted. Three solutions satisfying these requirements are reviewed, one for a more conventional technology, one for digital technology, and one for switched-capacitor technology. The first one of these is based on the use of efficient conversion circuits operating primarily in the continuous-time analog domain and the second one on a multistep single-path multiplier-free conversion scheme of a type which is particularly suitable for employing wave digital filters, including branching filters of that type. The third one makes use of an alternative of the second one which does not involve branching filters.