A MIC power amplifier with power combining based on InGaP/GaAs HBT is developed and measured for the application of the latest high power amplifier stage of the X-band. A novel InGaP/GaAs HBT power transistor with an on-chip RC stabilization network is used as the power combing cell to improve the stability of the circuit. A compact mi- crostripe line parallel matching network is used to divide and combine the power. By biasing the amplifier at class AB： Vc= 7V, Ic = 230mA,a maximum CW stabile output power of 28.9dBm and a power combine efficiency of 80% are achieved at 8. 1GHz.
An lnGaP/GaAs HBT microwave power transistor with on-chip parallel RC stabilization network is developed with a standard GaAs MMIC process. From the stability factor K, the device shows unconditional stability in a wide frequency range due to the RC network. The power characteristics of the device as measured by a loadpull system show that the large-signal performance of the power transistor is affected slightly by the RC network. Psat is 30dBm at 5.4GHz,and PldB is larger than 21.6dBm at llGHz. The stability of the device due to RC network is proved by a power combination circuit. This makes the power transistor very suitable for applications in microwavc high power ttBT amplifiers.
