All-digital aliasing-free PWM transmitter with reduced filtering requirements

The paper presents an All-Digital Aliasing-Free PWM (AF-PWM) transmitter, which combines multiphase band-limited PWM (MP-BLPWM) and accumulated N phase-shift pulse modulation (AN-PSPM), and its FPGA-implementation. As the architecture is based on MP-BLPWM, which generates finite harmonics PWM, this eliminates image and aliasing distortion, and improves spectral performance. However, finite harmonics PWM leads to large amplitude variation, which is converted to two voltage level signals using AN-PSPM, leading toward all-digital implementation. The transmitter's performance is experimentally validated for 5G-NR and LTE signals, both with and without a switched-mode power amplifier (Class-D PA). Measurement results demonstrate that, when used with the PA, the transmitter achieves ACLR values of 37.9 dBc for 5G-NR and 42.2 dBc for LTE signals. Furthermore, the EVM of the proposed transmitter with the Class-D PA is measured at 1.3% for 5G-NR and 0.9% for LTE, highlighting its effectiveness for advanced wireless communication applications.