A MONOLITHICALLY INTEGRATED HEMT-HBT LOW-NOISE HIGH LINEARITY VARIABLE GAIN AMPLIFIER

We report on a 1-6 GHz HEMT-MBT three-stage variable pain amplifier (V GA) which is realized using selective molecular beam epitaxy (MBE). Th e VGA integrates an HEMT low noise amplifier with an HBT analog curren t-steer variable gain cell and output driver stage to achieve a combin ation of low noise figure, wide gain control, and high linearity. The HEMT-HBT VGA MIMIC obtains a maximum gain of 21 dB with a gain control range > 30 dB, a minimum noise figure of 4.3 dB, and an input IP3 (II P3) greater than -4 dBm over 25 dB of gain control range. By integrati ng are HEMT instead of an HBT preamplifier stage, the VGA noise figure is improved by as much as 2 dB compared to an all-HBT single-technolo gy design. The HEMT-HBT MMIC demonstrates the functional utility and R F performance advantage of monolithically integrating both HEMT and HB T devices on a single substrate.