High dynamic range, triple gate-based compact DC-40 GHz variable attenuator MMIC for Ka-band variable gain amplifier ICs

The design and performance of a compact DC-40 GHz variable attenuator MMIC are reported in this paper. Using our standard 4-inch 0.25-/spl mu/m GaAs power PHEMT technology, this T-type attenuator exhibits more than 30-dB dynamic range, with a nominal insertion loss of 4 dB over the DC-40 GHz band By using triple-gate FETs, typical input power compression of more than 10 to 20 dBm is achieved with a die area of only 1 mm/sup 2/ (0.9/spl times/1.12 mm/sup 2/) and better overall performance. This MMIC is 30% smaller than any previously reported analog attenuators operating in the DC-40 GHz frequency range. This attenuator is used as well in a variable gain amplifier (VGA), specifically designed for Ka-band LMDS and VSAT radios. From 24 to 32 GHz, the VGA MMIC demonstrates a maximum gain of 32 dB, with more than 35-dB dynamic range and 24-dBm output power at 1-dB gain compression.