US 11,054,938 B2
Providing a baseline capacitance for a capacitance sensing channel
Denis Ellis, Cobh (IE); Kaveh Hosseini, Cork (IE); Timothy John Williams, Bellevue, WA (US); Gabriel Rowe, Kirkland, WA (US); Roman Ogirko, Lviv (UA); and Brendan Lawton, Cork (IE)
Assigned to Cypress Semiconductor Corporation, San Jose, CA (US)
Filed by Cypress Semiconductor Corporation, San Jose, CA (US)
Filed on Jul. 26, 2017, as Appl. No. 15/659,798.
Application 15/659,798 is a continuation of application No. 14/670,345, filed on Mar. 26, 2015, granted, now 9,746,974.
Claims priority of provisional application 62/040,120, filed on Aug. 21, 2014.
Prior Publication US 2017/0371451 A1, Dec. 28, 2017
This patent is subject to a terminal disclaimer.
Int. Cl. G06F 3/041 (2006.01); G06F 3/044 (2006.01)
CPC G06F 3/04166 (2019.05) [G06F 3/0446 (2019.05)] 16 Claims
OG exemplary drawing
 
1. A capacitance-sensing circuit comprising:
a channel input associated with measuring a capacitance of an element of a capacitive sense array; and
a capacitive hardware baseliner coupled to the channel input, wherein the capacitive hardware baseliner comprises:
a capacitor;
a programmable baseline resistor; and
a buffer with an input coupled to the programmable baseline resistor and an output coupled to the channel input, wherein the capacitive hardware baseliner generates a baseline current using the capacitor and the programmable baseline resistor to control a time constant of the capacitive hardware baseliner based on a time constant of the channel input associated with the measuring of the capacitance of the element of the capacitive sense array, wherein the capacitive hardware baseliner provides the baseline current at the channel input to provide a charge for a sense capacitor, wherein a change in the charge of the sense capacitor provided by the baseline current indicates a presence of a touch object proximate to the element.