A wideband CMOS variable gain low noise amplifier based on single-to-differential stage for TV tuner applications

Abstract

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 (6dB 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-μm 1P6M mixed-signal CMOS process. Measurements show that in the 50-860MHz frequency range, the VGLNA achieves 15dB maximum gain, 31dB variable gain range, a minimum 3.8dB noise figure and 2.6dBm 11P3 at 15dB gain while consumes 5.7mA from a 1.8V supply.