Design Of Dual-band RF Power Amplifier

Radio frequency power amplifier(RF PA) is one of the important parts of transmitter for wireless communication systems. Its performance influences the signal quality of communication directly. With the development of communication technology, people have been pursuing radio frequency devices with low power consumption, compact size and multi-functions. RF power amplifier is a mainly power consumption component with a large size in communication equipment. Therefore, it is valuable to study RF power amplifier with multiple operating frequencies to replace traditional RF power amplifier, which is only operating at a single frequency.Based on the multi-band microstrip transmission line impedance matching structure, a new dual-band impedance matching network of RF power amplifier is proposed. Its method is that the real part of admittance for input/output impedance of the amplifier at two different frequencies is transformed to the same value. Moreover, the imaginary part of input or output admittance of the transistor is matched by using the different stub line structure. Finally, the whole circuit can be matched at two frequencies through the real impedance matching structure, respectively. The transistor MRF6S27015 N is selected to design the class-AB dual-band RF power amplifier with the aid of ADS simulation software. The simulation results indicate that the amplifier can work correctly at 1.8GHz and 2.5GHz. When the input power is 23 d Bm, the output power is about 38.91 d Bm and 37.92 d Bm at two frequencies, respectively. The gains are about 15.91 d B at 1.8GHz and 14.92 d B at 2.5GHz, respectively. The power added efficiency(PAE) is about 43.84% and 33.22%, respectively. Meanwhile, an experimental class AB dual-band RF power amplifier is fabricated on the substrate with relative dielectric constant of 2.65 and thickness of 1mm through traditional PCB process. The measured results show that the gain about 11.0 d B at 1.8GHz and 8.6d B at 2.5GHz. The return loss is less than 10.7d B and 15.5d B at each frequency, respectively. Moreover, the transistor CGH400010 is chosen to design the dual-band RF power amplifier with operating frequencies of 2.4 GHz and 3.35 GHz, respectively. The simulation results indicate that the gains are about 12.70 d B and 12.38 d B, the output power are about 40.70 d Bm and 40.38 d Bm, and the power added efficiency(PAE) are about 55.60% and 67.94% with the input power of 28 d Bm.