Abstract: An ultra-high bandwidth power amplifier (PA) was designed for very-high-frequency (VHF) and ultra-high frequency (UHF) applications based on 0.15 um GaAs PHEMT technology. The PA works in class AB, which consists of two symmetrical branches from top to bottom. The output circuit uses T-junction technology which uses the Rogers 4350B high-speed printed circuit board (PCB) in the off-chip. Finally, the chip and PCB have co-simulated in Advanced Design System (ADS). The simulation results show that the PA achieves an operating bandwidth of 30 MHz to 3 GHz whose bandwidth is more than 6 octaves. The small signal gain is over 21 dB±0.3 dB the whole bandwidth and the input and output return loss is generally less than -10 dB. Under continuous wave measurement, the saturated output power is 30.9 dBm±0.5 dB and the power added efficiency (PAE) is 17.7%-14.0%.