1.8 V-100 MHz CMOS programmable gain amplifier

This paper presents a low-voltage low-power differential programmable gain amplifier (PGA) for wideband applications. The proposed cell is based on a g_m-boosted source degenerated differential pair with a hybrid polysilicon-MOS resistor degeneration structure. Fabricated in a 0.35 mum CMOS technology, the PGA consumes less than 0.5 mW at a single 1.8 V supply. Measured results for a 3-bit implementation show a 0 to 18 dB linear-in-dB programmable gain with a constant bandwidth of 100 MHz when driving 150 fF capacitive loads. Distortion levels are below -72 dB over the whole gain range at 10 MHz for a 0.2 V_p-p differential output