A novel stacked amplifier scheme for expansion of 1-dB compression output power level

Abstract

A three-stage current-reuse PHEMT amplifier with a stacked scheme in it (Stacked Triple-HEMT amplifier) is newly proposed. The output voltages of the second (lower) PHEMT and the source-line-connected third (upper) one are designed to be in phase for the best series power combining. Due to this reason, the proposed Triple-HEMT amplifier (Vd = 7.5V) potentially increases the output power level by more than 3dB compared with non-stacked Dual-HEMT amplifier (Vd = 5V). When the gate width of each PHEMT is same, the achieved Pmb improvement was nearly 5dB. Because the circuit area can be same as the non-stacked one, this series-combining technique is also effective to save the area of amplifier MMIC by more than 50% compared to the parallel-combining one.