| 摘要 |
The present invention provides a capacitive sensing circuit, comprising at least one capacitor to be measured, an integral capacitor, a first current mirror having a first current path and a second current path. A first current is generated in the first current path so as to charge the capacitor to be measured, while a second current mirrored from the first current is generated in the second current path so as to charge the integral capacitor. As such, the mirrored current, resulted from mirroring the charging current on the capacitor to be measured, is used to charge the integral capacitor. Charge energy charged on the capacitor to be measured may be copied onto the integral capacitor so as to reflect a voltage signal. Subsequently, capacitance variation generated when the capacitor to be measured is touched may be sensed by detecting the voltage signal. |
| 主权项 |
1. A capacitive sensing circuit for sensing capacitance variation with charge clone, comprising:
a first current mirror comprising a first current path and a second current path; at least one capacitor to be measured; an integral capacitor connected to said second current path; a first switch, connected between said capacitor to be measured and said first current path, turning on wiring between said first current path and said capacitor to be measured when said first switch is closed, such that a first current is generated in said first current path to charge said capacitor to be measured, and meanwhile, a second current mirrored from said first current is generated in said second current path to charge said integral capacitor, thus copying charge energy charged on said capacitor to be measured onto said integral capacitor and generating a voltage signal on said integral capacitor; and a second switch, connected between said capacitor to be measured and the ground, operatively switched reversely with respect to said first switch, such that wiring between said first current path and said capacitor to be measured is opened, while wiring between said capacitor to be measured and the ground is turned on for discharging said capacitor to be measured, when said first switch is opened while said second switch is closed. |
