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A wideband CMOS variable gain low noise amplifier (VGLNA) used for TV tuner is presented. A single-to-differential (S2D) circuit other than an off-chip balun is applied for high gain mode and a resistive attenuator is for five steps (6 dB per step) attenuation in low gain mode. The performance of S2D, especially the noise factor is analyzed. The chip is implemented in a 0.18-mum 1P6M mixed-signal CMOS process. Measurements show that in the 50-860 MHz frequency range, the VGLNA achieves 15 dB maximum gain, 31 dB variable gain range, a minimum 3.8 dB noise figure and 2.6 dBm 11P3 at 15 dB gain while consumes 5.7 mA from a 1.8 V supply.