A New GaAs Multi-Chip MMIC C-Band Variable Gain Amplifier for Point to Point Wireless Communication Systems

In this paper a new GaAs Multi-Chip MMIC CBand Variable Gain Amplifier (VGA) is presented for point to point wireless communications systems. The VGA is composed of three dies: the first is an input stage amplifier, the second is a variable voltage controlled attenuator (VVA), and the last is an output stage amplifier. In order to achieve high linearity, low distortion, and broad bandwidth, parallel feedback topologies are employed in both input and output amplifiers. The VVA, based on p-networks, comprises a design by stacking multi-gate MESFETs in each arm of the VVA to minimize harmonics and distortions, enhance the linearity of the VGA. The VGA is implemented in M/A-COM Technology Solutions (M/A-COM Tech) Fab1 process: amplifiers are fabricated in 0.5um pHEMT power process, VVA is in 1.0um MESFET high linearity switch process. The VGA, complex multifunction and multichip MMICs, exhibits unmatched performance of 20dB gain, 35dB attenuation range, 12dB input return loss, 15dB output return loss, 3.0dB noise figure, provides 31dBm output third order inter-modulation product, and 19dBm 1dB gain compression point over 4.9 to 8.5GHz while consuming only 98mA DC current at + 5V supply voltage. The VGA is packaged in a 4 x 4 mm PQFN package.