Patent ID: 7155178

Claim:
A circuit system for wireless communications, the system transmitting and receiving radio frequency (RF) signals via a first and second antenna, comprising: a printed circuit board having a predetermined area devoid of a solder mask; an antenna switch, mounted on the printed circuit board within the predetermined area, having at least two input ports and at least two output ports, enabling connection of any of the input ports to either of the output ports, where the output ports are coupled to the first and the second antennas, respectively; a first filter, mounted on the printed circuit board within the predetermined area and coupled to one of the input ports of the antenna switch, blocking unwanted frequency components in an RF receive signal from either of the antennas; a first matching network transforming the RF receive signal from single-ended to differential; a converter converting a baseband transmit signal from digital to analog; a transceiver down-converting the RF receive signal supplied by the first matching network to a baseband receive signal, and up-converting the baseband transmit signal passing through the converter to an RF transmit signal; a second filter coupled between the converter and the transceiver, matching an output impedance of the converter to an input impedance of the transceiver; a second matching network transforming the RF transmit signal from differential to single-ended; and a power amplifier, mounted on the printed circuit board within the predetermined area and coupled between the second matching network and the other input port of the antenna switch, boosting the RF transmit signal from the second matching network, whereby the RF transmit signal undergoing the boost is transferred to either antenna through the antenna switch; wherein the first matching network is coupled between the first filter and the transceiver, and the second matching network is coupled between the transceiver and the power amplifier; wherein each matching network, having a common node and a pair of differential nodes, includes a first capacitor connected between the common node and a first node of the differential nodes, a first inductor connected between the first node of the differential nodes and ground, a second inductor connected between the common node and a second node of the differential nodes, a second capacitor connected between the second node of the differential nodes and ground, and an adjustable inductor connected across the differential nodes and in parallel with the transceiver.