Patent attributes
Methods, devices, and systems that measure capacitance are disclosed. Typically, an accumulator circuit couples to the capacitance and includes an accumulator and switch(es) that charge the accumulator over a series of switch-controlled charging or discharging cycles governed by a first control signal. The accumulator circuit provides an accumulator signal based on the charge on the first accumulator. A discharge circuit couples to the accumulator circuit and includes an optional variable current device, the discharge circuit partially discharging the accumulator based on a second control signal. A control circuit, which couples to the accumulator circuit and the discharge circuit, dynamically adjusts the first and/or second control signals to keep the accumulator signal in a desired range. The dynamically adjusted control signal can be used as a measure of the capacitance. Such methods and systems may be used in capacitive touch sensing devices such as capacitive buttons and capacitive touch panels.
