A transistor comprises a drain, a gate, a source, a body terminal and a body resistance. The drain is connected to a supply voltage line to receive a supply voltage. The gate is connected to a control voltage line to receive a control voltage. The source is connected to a input line to receive a input radio frequency signal. The body terminal is connected to the drain. The body resistance is disposed between the drain and the body terminal. By the foregoing configuration, the leakage current of the substrate is reduced and the threshold voltage of the transistor is reduced to conform to the present low power design.