12.5 2D Coded-aperture-based ultra-compact capacitive touch-screen controller with 40 reconfigurable channels

This paper presents an ultra-compact, low-power and noise-immune mutual-capacitance TSP controller based on a 2D coded-aperture read-out architecture. Figure 12.5.1 shows conceptual diagram of the read-out method, which obtains a TSP´s response to a set of 2D basis patterns, based on the widely known notion that all kinds of 2D images can be transformed into other orthogonal basis domains, e.g., frequency or pseudo-random noise. Sensing whole TSP channels projected into a single-channel circuit prevents hardware redundancy due to a requirement for parallel circuits and enables designers to focus on maximizing noise-filtering performance with less concern about hardware cost. Note that even with a single-channel circuit, this method facilitates all mutual-capacitor-nodes to be driven simultaneously, therefore fully retaining high noise-immunity advantages of the previously reported CDMS method.