Partitioning analog and digital processing in mixed-signal systems

Shrinking feature sizes, combined with the need for low-power and lightweight components, fuel the desire to place large mixed-signal systems onto a single die. A major design issue in mixed-signal systems is the effect of digital switching noise coupled to sensitive analog circuits through the substrate. A method is presented for minimizing this effect by partitioning digital and analog processing into separate time blocks. The resulting trade-off between lost signal and increased energy consumption is explored. As an example, a GPS synchronizer design is analyzed with respect to modifications that can be made to increase performance, while minimizing any associated energy penalty. Application of the partitioning method to other communications systems is discussed.