A V-Band Stacked HEMT Power Amplifier With 25-dBm Saturated Output Power in 0.1-mu m InGaAs Technology

A stacked high-electron mobility transistor (HEMT) power amplifier (PA) has been designed and implemented in a commercial 0.1-mu m InGaAs pHEMT process to increase gain and output power at millimeter-wave frequencies. The stability problem of the stacked HEMT has been analyzed. A new layout of the stacked HEMT for improving the high frequency stability is proposed and used in the PA design. Measurements on the three-stage PA with parallel devices verify the saturated output power of 25 dBm and the maximum power added efficiency of 15% at 61 GHz, which is the highest reported output power of stacked HEMT PAs. The chip size measures 3.2 mm(2) which makes this the most power dense V-band amplifier reported from GaAs with 100 mW/mm(2)