The memory 806 can be used for a wide variety of purposes, such as storing data and/or instructions to facilitate the operation of the mobile device 800 and/or to provide storage of user information.

The power management system 805 provides a number of power management functions of the mobile device 800. The power management system 805 can include an MLS envelope tracker 860 implemented in accordance with one or more features of the present disclosure.

As shown in FIG. 7, the power management system 805 receives a battery voltage form the battery 808. The battery 808 can be any suitable battery for use in the mobile device 800, including, for example, a lithium-ion battery.

FIG. 8 is a schematic diagram of one embodiment of a communication system 950 for transmitting RF signals. The communication system 950 includes a battery 901, an MLS envelope tracker 902, a power amplifier 903, a directional coupler 904, a duplexing and switching circuit 905, an antenna 906, a baseband processor 907, a signal delay circuit 908, a digital pre-distortion (DPD) circuit 909, an I/Q modulator 910, an observation receiver 911, an intermodulation detection circuit 912, an envelope delay circuit 921, a coordinate rotation digital computation (CORDIC) circuit 922, a shaping circuit 923, a digital-to-analog converter 924, and a reconstruction filter 925.