Variable gain amplifiers (VGA) used in the front ends of receivers need to amplify large signals with high linearity. An amplifier was designed with an improved gm-boost circuit and increased transconductance of the input metal oxide semiconductor (MOS) transistor which reduces the distort ion caused by the drain-source voltage variation. A symmetrical variable resistor structure was used to further reduce the non-linearity from the MOS switch. Simulation results show that the amplifier consumes 1.5mW at 3.3V. The total harmonic distort ion of a 3.3V differential output signal is less than - 60 dB f or frequencies from 1 to 10MHzan d volt age gains from 3 to 24dB.