In some embodiments, the first filter includes at least one series inductor and at least one shunt capacitor. According to a number of embodiments, the first filter further includes a DC blocking capacitor in series between the modulator output voltage and the power amplifier supply voltage.

In various embodiments, the second filter includes at least one series inductor and at least one shunt capacitor.

In several embodiments, the envelope tracker further includes a controllable delay circuit configured to control a relative delay between an AC path through the first filter and a DC path through the second filter. According to a number of embodiments, the controllable delay circuit includes a plurality of controllable delay buffers each configured to control a delay of a respective one of the plurality of regulated voltages.

In various embodiments, a DC path through the second filter carries at least seventy five percent of the energy provided from the envelope tracker to the power amplifier.

In certain embodiments, the present disclosure relates to an envelope tracker. The envelope tracker includes a power amplifier supply voltage terminal configured to output a power amplifier supply voltage, a DC-to-DC converter configured to output a plurality of regulated voltages based on regulating a battery voltage, a modulator configured to generate a modulator output voltage based on the plurality of regulated voltages and an envelope signal, an AC path filter coupled between the modulator output voltage and the power amplifier supply voltage, and a DC path filter coupled between a DC voltage and the power amplifier supply voltage.