A 300-800 MHz CMOS radio receiver aiming at software-defined radio is proposed. It exploits an LNA preceded by a tunable LC filter with one external coil to achieve voltage amplification for low NF and low-pass filtering to improve the 3rd and 5th harmonic rejection of an RF-sampling receiver to > 60dB. The balun-LNA provides partial IM3 compensation, to drive a wideband sampling downconverter. The measured gain is 22-28dB while NF ranges from 0.8-4.3dB. The core consumes 6mW and clock takes 12mW.