Research on Power Amplifiers and Transmitter with Wide Signal Bandwidth, High Linearity, and Low Memory Effect for 5g Small Cell Applications(2/3)

This three-year project intends to develop power amplifiers and RF transmitter that can be applied in the bands n77 to n79 of the 5G NR FR1 band. The project will adopt GaN and CMOS processes to implement the fifth-generation mobile communications small base station (n77) and handheld device transmitter (n79), respectively. The goal of the project is to develop the design flow for a high power amplifier with wide bandwidth, high power added efficiency (PAE), high linearity, and low memory effects that can comply with the modulated signal bandwidth up to 100 MHz. The project divides into two parts. In the first year, we will adopt class-J and Doherty architectures to realize two 9-W GaN power amplifiers. The characteristics of the amplifiers are called for wideband, high linearity, and low memory effects for small cell base station. In the second year, the developed GaN power amplifiers will be integrated into the printed circuit board as module, which the bias circuit modulation and heat dissipation problems will be dealt with to verify the eliminations of the electrical and electro-thermal memory effects. After then, we will observe the improvements of linearity. Meanwhile, the average power tracking technology is used to improve the power efficiency (PAE). Finally, the digital predistortion (DPD) is used to further improve the adjacent channel power ratio (APCR) and error vector amplitude (EVM). The second part will design a high integration, high linearity, and low memory effects transmitter for the n79 band in the second year. It is proposed to use stacked power amplifier architecture, with the goal of being suitable for class 3 power levels. Without the expensive BAW filter placed in front of transmitter, our goal is to reduce the ACPR of the RF transmitter to avoid the interference with indoor WiFi-6 bands in the 5.2 GHz band. In the third year, the developed n79 RF transmitter chip is then integrated root-mean-square power detector and DC-to-DC converter into the printed circuit board as a transmitter module which average power tracking technology will be applied to improve the PAE under different modulation signals. Finally, DPD technique is used to further improve the performances of ACPR and EVM.