| 摘要 |
A portable terminal includes: a key row including a reference resistor, switches separately connected to the reference resistor, and a plurality of resistors connected to the switches, respectively; a reference voltage unit connected to the reference resistor and providing a reference voltage; and a first comparator and a second comparator dividing the reference voltage from the reference voltage unit by the reference resistor and at least one resistor connected to an activated switch, and receiving an analog key input signal corresponding to the divided reference voltage. |
