A low supply voltage CMOS variable-gain low noise amplifier (LNA) is presented in this paper. A folded cascode structure is used to reduce the supply voltage to only 1 V. The conversion gain of the LNA can be controlled by the bias voltage of the connon-gate transistor. When the input signal is weak, the circuit works at high-gain mode to improve the sensitivity. Otherwise, when the input signal is strong, the circuit works at low-gain mode to increase the linearity.