Abstract: The present invention discloses an antenna diversity switch, used for receiving and transmitting RF signals for dual-mode co-existence wireless communication system. The antenna diversity switch comprises a first transmitting port; a second transmitting port; a receiving port; a first control unit, electrically connected between the first transmitting port and a first antenna; a second control unit, electrically connected between the first transmitting port and a second antenna; a third control unit, electrically connected between the second transmitting port and the first antenna; a forth control unit, electrically connected between the second transmitting port and the second antenna; a fifth control unit, electrically connected between the receiving port and the first antenna; a sixth control unit, electrically connected between the receiving port and the second antenna. The antenna diversity switch according to the present invention meets the requirement of IEEE 802.

Abstract: A charge control system for lithium battery using pulse width modulation is provided, and it detects the existing voltage of the charging lithium battery by a voltage detector and passes this voltage value to a microprocessor preset in the hand-held apparatus. Thus, the microprocessor can decide the applicable charge stage and confirm the status of the charging battery depending on the different Voltage values in real time. Next, the microprocessor controls a control unit by a pulse width modulation signal to modulate the power-source, which comes from an adaptor, as a constant current or a constant voltage to charge the battery. Accordingly, the charge process is completed by repeating the voltage detection and the duty cycle modulation of the control unit.