US 11,875,006 B1
Self-capacitor sensing using alternating-current-mode bridge for capacitive touch panels
Chao Yang, San Diego, CA (US); Mohamed Elsayed, San Diego, CA (US); and Dazhi Wei, San Diego, CA (US)
Assigned to Shenzhen Goodix Technology Co., Ltd., Shenzhen (CN)
Filed by Shenzhen Goodix Technology Co., Ltd., Shenzhen (CN)
Filed on Mar. 21, 2023, as Appl. No. 18/187,648.
Int. Cl. G06F 3/045 (2006.01); G06F 3/044 (2006.01); G06F 3/041 (2006.01)
CPC G06F 3/0446 (2019.05) [G06F 3/0418 (2013.01); G06F 3/04166 (2019.05); G06F 3/0445 (2019.05); G06F 2203/04111 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A system for self-capacitor sensing in a touch panel array integrated with a display panel, the system comprising:
an alternating-current-mode (AC-mode) bridge comprising:
an error amplifier to generate a loop control voltage responsive to a sinusoidal driver signal and an error feedback signal;
a first branch to couple with an ith channel of a touch panel array having an ith channel self-capacitance (Ci_i), and a second branch to couple with a jth channel of a touch panel array having a jth channel self-capacitance (Ci_j);
a set of adjustable current sources configured, based on the loop control voltage, to output a first sinusoidal current to the first branch and to output a second sinusoidal current to the second branch,
wherein the first branch manifests a first branch voltage responsive to applying the first sinusoidal current to Ci_i, and the second branch manifests a second branch voltage responsive to applying the second sinusoidal current to Ci_j, the error feedback signal being a function of the first branch voltage and the second branch voltage; and
an output amplifier to generate an ith output voltage (Vout_i) based on a difference between the first branch voltage and the second branch voltage.