To reduce the loss caused by power imbalance between switched-mode power amplifier (SMPA) units of all-digital transmitters (ADTx), this paper proposes an all-digital transmitter structure with power equalization and harmonic elimination. Based on the third and fifth harmonic cancellation, this structure achieves output power equalization of SMPA by controlling the width of 3-level sub-pulses to be the same. Moreover, the equalization of each switch transistor is realized by outphasing method. Finally, the feasibility of the method is verified by simulation results. For different input signals with a carrier frequency of 200 MHz, the proposed structure achieves the same output power of each SMPA unit.

To reduce the power loss of the SMPA unit, this paper proposes a power equalization RF-PWM method with third and fifth harmonic elimination. Based on the third and fifth harmonic cancellation, this method achieves output power equalization of SMPA by controlling the width of 3-level sub-pulses to be the same. Moreover, the equalization of each switch transistor is realized by outphasing architectures. Finally, the feasibility of the method is verified by simulation results. For QPSK and 16QAM signals with a carrier frequency of 200 MHz, the proposed method achieves the same output power of each SMPA unit.

To relax the requirement of the filter and reduce the control complexity of the SMPA, this paper proposes a 5-level RF-PWM method for all-digital transmitters with 3rd and 5th harmonic elimination. The method is achieved by changing the threshold signal to control the pulse width of the 3-level sub-pulses. Finally, the feasibility of the method is verified by simulation. For the 16QAM signal with a carrier frequency of 200MHz, the proposed method can achieve -46.24dBc and -54.05dBc respectively when the coding efficiency reaches 77.51%.