A Digitally Reconfigurable Sensor Interface for SOC using Delta-Sigma Modulators

Many systems on chip (SOC) applications require a mixed signal (analog and digital blocks) design approach. The incorporation of some degree of analog programmability in current digital reconfigurable devices is desired, so the same processor platform can be used in different applications. As mixed signal SOC applications deal with heterogeneous signals (low and high frequency) and signal processing functions (linear and non-linear), the ideal analog interface architecture should be able to manage this heterogeneity. In this paper we propose the use of a constant analog architecture for the SOC analog interface, able to deliver constant performance in this heterogeneous environment. The proposed approach is based on a set composed by a mixer and a band-pass SigmaDelta modulator. Several linear and nonlinear applications can be mapped over the proposed interface architecture for processing analog input signals ranging from low to high frequency. A prototype was built and characterized. Practical results show constant and predictable performance over a large frequency range of the input signal. The achieved results also support the interface potential use for general analog interfacing and programmable signal processing