Patent ID: 9257737
Filing Date: 2016-02-09
CPC Classification: H01Q,H04B

Claim Text:
1. An antenna switching circuit, disposed in an electronic device comprising an internal antenna and a radio frequency (RF) module, the antenna switching circuit comprising: a first reference signal source having a first ground signal; a second reference signal source having a first reference signal; a third reference signal source having a second reference signal; an external antenna connector comprising a connection terminal and an independent ground terminal, wherein the external antenna connector is configured to be selectively electrically connected to a connector of an external antenna when the electronic device is connected to a docking device, arranged such that when the external antenna connector is not electrically connected to the connector of the external antenna, the connection terminal and the independent ground terminal are not electrically connected, the independent ground terminal has a second ground signal that is the first reference signal, and the connection terminal has a third ground signal, and when the external antenna connector is electrically connected to the connector of the external antenna, the connection terminal and the independent ground terminal are electrically connected, and the independent ground terminal and the connection terminal share the first ground signal such that the second ground signal and the third ground signal are equal to the first ground signal; a switch unit having a control terminal connected to the second reference signal source, a first terminal connected to the third reference signal source, and a second terminal connected to ground; and a controller, having a first RF terminal, a second RF terminal, a first control terminal, and a second control terminal, wherein the first RF terminal is electrically connected to the RF module, the second RF terminal is electrically connected to the internal antenna, wherein the first control terminal and the second control terminal of the controller are respectively connected to the first terminal and the control terminal of the switch unit, and configured to respectively detect the second reference signal and the second ground signal; wherein when the electronic device is not connected to the docking device, the second reference signal source provides the first reference signal to the control terminal of the switch unit, the second ground signal has a logic high level, the second ground signal turns on the switch unit so that the first control terminal of the controller is connected to the ground, and the second reference signal has a logic low level; wherein when the electronic device is connected to the docking device, the control terminal of the switch unit is coupled to the ground according to the second ground signal, the second ground signal turns off the switch unit so that the first control terminal of the controller is directly connected to the third reference signal source, and a voltage level of the second reference signal is pulled up to the logic high level; and wherein the controller is configured to electrically connect the RF module to the internal antenna when the controller detects the second ground signal has the logic high level and the second reference signal has the logic low level, and to electrically connect the RF module to the external antenna when the controller detects the second ground signal is changed to the logic low level and the second reference signal is changed to the logic high level.