Resonant line driver including energy transfer inductor for driving capacitive-load lines

Abstract

A resonant line driver for driving capacitive-loads includes a driver series-coupled to an energy transfer inductor L, driving signal energy at a signal frequency through L. A switch array is controlled to switch Lbetween multiple electrodes according to a switching sequence, each electrode characterized by a load capacitance CL. Land CL form a resonator circuit in which signal energy cycles between Land CL at the signal frequency. The switch array switches Lbetween a current electrode and a next electrode at a zero_crossing when signal energy in the energy transfer inductor is at a maximum and signal energy in the load capacitance of the current electrode is at a minimum. An amplitude control loop controls signal energy delivered to the LCL resonator circuit, and a frequency control loop controls signal frequency/phase. In an example application, the resonant driver provides line drive for a mutual capacitance touch screen.