Improved Pulse Edge Independent Distribution Method for High PAPR High Bandwidth Envelope Tracking Power Supply

Envelope tracking (ET) power supply provides the power amplifier (PA) with a dynamic supply voltage that tracks the envelope of the input signal to the PA, and the final PA efficiency can be greatly improved. With the ever-advancing tracking bandwidth, the switching frequencies of ET power supplies are pushed to be very high and even difficult to be implemented. To address this issue, the pulse edge independent distribution (PEID) method has been proposed. Based on the idea of alternatively working by sets, the control pulses for the multilevel converter are broken into independent rising and falling edges, and rematching them with optimized new sequences can achieve a 1/ n ( n \in N ) ratio of the switching frequency over envelope bandwidth. However, each increase of n by 1 means that a whole set of voltage cells is added, leading to a great increase in system complexity and cost, especially for high peak-to-average power ratio (PAPR) applications. Besides, due to the irregular and aperiodic feature of the real communication envelope, the PEID control logic may suffer from surplus and imbalance in switching frequency reduction. Thus, this article proposes an improved PEID method. Assisted by the digital control platform, the control logic is redesigned, which can realize a balanced distribution of the rising and falling edges for arbitrary envelopes. Moreover, it can extend the domain of the 'n' to noninteger, achieving a more subtle resolution of PEID. On this basis, an evaluation function is constructed taking into account the efficiency, voltage-cell quantities, and switching frequency. With the desired weighted coefficients, an optimized comprehensive performance can be achieved. A prototype with 2-27-V output voltage range, 10- and 20-MHz tracking bandwidths, and 8.5-dB PAPR is fabricated and tested in the lab. The experimental results validate the proposed method.