In an input/output circuit (200), a differential balun (250) is provided that has first and second balun inputs and first and second balun outputs. An antenna (230) is connected to the first and second balun outputs. A differential amplifier (220) has one output connected to the first balun input, and a second output connected to the second balun input, while a single-ended amplifier (110) has its input connected to the first balun input. A grounding switch (240) is connected between the second balun input and ground. During a transmit mode the grounding switch (240) is open, the differential amplifier (220) is turned on, and the single-ended amplifier (110) is turned off. During a receive mode the grounding switch (240) is closed, the differential amplifier (220) is turned off, and the single-ended amplifier (110) is turned on.