Design methods for system-on-a-chip control codecs to enhance performance and reuse

While the conventional concept of a signal coder-decoder (codec) is of a homogeneous device, such that the output decoding is simply an inverse of the input decoding, the heterogeneous codec developed in this paper decouples the input and output decoding; this variation generalizes the system. A control codec is an application of a heterogeneous codec, which replaces a traditional discrete analog control loop. This analog control loop includes an A/D (coder) plus a D/A (decoder), as well as other peripheral signal processing algorithms. Our application of the control codec is to improve the control of RF transponders in satellites. The codec is shown to have the ability to be optimized for a specific application as well as to be re-targeted to different fabrication lines. Because of the environmental demands on spaceborne devices several stable radiation-hardened SOI BiCMOS processes were used. The MIT Lincoln Labs AST Fully Depleted SOI deep-submicron process was also used as an example of re-targeting. Further, we develop the design for a control codec as an application of a general class of heterogeneous, process-independent codecs. The concepts for both a heterogeneous codec and a control codec are important additions to mixed-signal system design because they facilitate analog and mixed-signal block reuse. Our methodology implements a deliberate mixed-signal design decomposition, which enhances the reuse. This reuse is a major advancement in the development of evolvable hardware that uses both analog and digital signal processing in SoC applications.