Continuous Time digital systems with Asynchronous Sigma Delta Modulation

Continuous Time (CT) digital signal processing offers several advantages compared to the Discrete Time (DT) approach, while keeping the classical advantages of the latter system. When applying CT Digital Signal Processing (DSP), the signals are digitized in amplitude but processed continuously in time. Since the required chip area for the CT delay lines is quite large, a common way for word length reduction of the CT DSP system input is to apply Delta Modulation (DM). Thus the delay lines must be designed only for a word length of one bit. In this contribution it will be shown that digitization by Asynchronous Sigma Delta Modulation (ASDM) can result in several advantages for CT signal processing. Using this novel approach the word length of the signal to be processed is also one bit. Nevertheless, compared to the DM system, several advantages such as improved performance and reduced hardware complexity can result.