Abstract—A high dynamic range RF variable gain amplifier\n(RFVGA) suitable for mobile digital television (DTV) tuners is\npresented. Variable gain is achieved using a capacitive attenuator\nand current-steering transconductance ( ) stages, which provide\nhigh linearity with relatively low power consumption. A novel\nbroadband input impedance matching scheme based on resistive\nshunt-feedback is proposed. This scheme allows the RFVGA to\nachieve a low noise figure. A gain control technique suitable for\nCMOS current-steering variable gain amplifiers is described; it\nfeatures 1 dB per step resolution, independent of process and temperature\nvariations. The chip is fabricated in six-metal 0.18 m\nCMOS technology and consumes 12.2 mA current from 1.8 V\nsupply. The RFVGA achieves 16 dB maximum gain, 33 dB gain\ncontrol range, a 4.3 dB noise figure, and an IIP3 higher than\n25 dBm.

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