公开(公告)号：US20140021966A1

公开(公告)日：2014-01-23

申请号：US13843129

申请日：2013-03-15

Applicant: SYNAPTICS INCORPORATED

Inventor： Farzaneh SHAHROKHI ,  Adam SCHWARTZ ,  Shahrooz SHAHPARNIA ,  Joseph Kurth REYNOLDS ,  Tracy Scott DATTALO

IPC: G01R27/26

CPC classification number: G01R27/2605 ,  G01D5/24 ,  G06F3/0416 ,  G06F3/044

Abstract: A differential amplifier has an output and differential first and second inputs. A switch disposed between a sensor electrode and the second input is opened to initiate a reset phase where the sensor electrode and the differential amplifier are decoupled. A feedback capacitance disposed between the second input and the output is reset to a first level of charge. The switch is closed to initiate a measurement phase where the second input and sensor electrode are coupled. In the measurement phase: charge is balanced between the sensor electrode and the feedback capacitance such that a sensor electrode voltage equals a voltage of the first input equals a voltage of the second input, and the sensor electrode is charged; and the differential amplifier is utilized to integrate charge on the sensor electrode, such that an absolute capacitance corresponding to a coupling between the sensor electrode and an input object is measured.

Abstract translation: 差分放大器具有输出和差分第一和第二输入。 设置在传感器电极和第二输入之间的开关被打开以启动复位阶段，其中传感器电极和差分放大器被去耦合。 设置在第二输入和输出之间的反馈电容被复位到第一电荷水平。 开关闭合以启动第二输入和传感器电极耦合的测量阶段。 在测量阶段：在传感器电极和反馈电容之间平衡电荷，使得传感器电极电压等于第一输入的电压等于第二输入的电压，并且传感器电极被充电; 并且差分放大器用于在传感器电极上集成电荷，使得测量对应于传感器电极和输入对象之间的耦合的绝对电容。