Circuit-level considerations for mixed signal programmable components

This paper presents some architectural studies regarding mixed signal programmable components (FPGAs or gate arrays). The effect of programmability through the use of switches is analyzed, and it is shown that the result is a transfer function modification when real characteristics of the switches are assumed. Moreover, the paper proposes the use of externally linear, internally nonlinear analog circuits, since this procedure could eliminate the error introduced by the switches. Using this approach, analog area is greatly reduced, and circuits can be built on top of digital technologies. Some experimental results in the analog and digital domain support the proposed approach to mixed circuit reprogrammability, being the basis for a mixed signal FPGA.