Nodal analysis of switched-capacitor networks

Abstract

Switched-capacitor (SC) networks comprise capacitors interconnected by an array of periodically operated switches. Such networks are particularly attractive in light of the high circuit density possible with MOS integrated circuit technology and hybrid integrated circuits using thin-film and silicon technology. The paper describes the analysis of SC networks by using nodal charge equations. It is shown that SC networks are time-variant sampled-data networks, which can be viewed as tandem connected four-ports in the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</tex> -domain. One pair of ports is viewed as a signal path corresponding to the even time slots, the other pair of ports as a path corresponding to the odd time slots of the periodically operated switches. In a subsequent publication the authors will show how four-port equivalent circuits in the z-domain of six basic building blocks can be used for the description of any SC network. This method allows the direct use of traditional network analysis tools like the transmission matrix for deriving transfer functions. The method ultimately leads to a two-port analysis of SC networks in which conventional two-port theory can be applied.