Methods and apparatuses for providing sensing signals for projected capacitive touch sensing using a differential current mode analog circuit

Abstract

An analog front-end circuit comprising: a first current mode differential charge amplifier for a first sensing line, comprising: a unity gain buffer with current replication circuit, wherein the first sensing line current being fed to the unity gain buffer with current replication circuit to generate a pull up and a pull down output currents; and a current mirroring and amplification circuit, wherein the pull up and pull down output currents being fed to the current mirroring and amplification circuit to generate a positively scaled and a negatively scaled output currents; a current combining circuit for combining the positively scaled output generated for the first sensing line and a negatively scaled output current generated for a second sensing line to generate a differential current; and a differential current-to-voltage converter for converting the differential current to an output voltage usable by touch controller application.