Patent ID: 8279018

Claim:
An apparatus comprising: a balun coupled to an antenna, the antenna configured to transmit and receive radio frequency signals, the balun comprising: a first inductor including a first set of ports coupled to the antenna; a second inductor including a second set of ports coupled to a power amplifier through a first circuit, the power amplifier configured to transmit a first signal to the antenna; a third inductor including a third set of ports coupled to a low noise amplifier through a second circuit, the low noise amplifier configured to receive a second signal from the antenna, wherein: the second set of ports is coupled to the first circuit, the third set of ports is coupled to the second circuit, the first circuit is separate from the second circuit, and a first coupling coefficient of mutual inductance between the first inductor and the second inductor is a first value, a second coupling coefficient of mutual inductance between the first inductor and the third inductor is a second value, and a third coupling coefficient of mutual inductance between the second inductor and the third inductor is a third value, the third value being lower than the first value and the second value.