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Long-term-evolution (LTE) communication enables high data-rates but degrades the efficiency of the power amplifiers (PAs) due to high peak-to-average power ratios of transmitted signals. Envelope tracking (ET) and envelope-elimination-and-restoration (EER) techniques have been proposed to improve the PA efficiency by adapting the PA supply voltage to the envelope. Linear PAs in ET systems are mostly implemented in non-CMOS technologies for high efficiency [1]. However, the growing demand for low-cost integrated systems has motivated the use of CMOS PAs [2]. The main drawback of this is that linear CMOS PAs have poor efficiency. The high efficiency of switching PAs makes them a promising candidate in CMOS [3]. In EER systems, where switching PAs are used, the supply modulator must satisfy stringent noise and bandwidth specifications in order to recover the amplitude information of the LTE …