MAX2674/MAX2676 features low noise and high linearity LNA and an antenna switch including circuitry supporting bias to accommodate external LNA applications. The autodetection circuit is used to detect the current of ANT. When no current is drawn from ANT, the switch defaults to normal LNA operation. The ANT pin can be directly connected to an external active antenna. The device automatically switches to the ANT input when an external active antenna is connected, in this case, the LNA will be bypassed. You can see this switch in the typical operating circuit on page 1,connected at pin A2.