Apparatus and method for modulating supply for a power amplifier

A method for generating a supply voltage in a power supply modulator including a Switching Mode Power Supplier (SMPS) module and a linear regulator, the method comprising:

• detecting a voltage of an input signal of the SMPS module;
• selecting at least one of a plurality of power supplies that have different voltages included in the SMPS module according to a voltage level of the input signal of the SMPS module;
• and
• generating a current for a power amplifier by using the selected power supply,
• wherein a current of a modulated power supply signal is generated by the SMPS module, and
• wherein a source current for supplementing an insufficient amount of the current generated by the SMPS module and a sink current for eliminating an excessive amount of the current generated by the SMPS module are generated by the linear regulator.

An apparatus for power supply modulation, the apparatus comprising:

• a Switching Mode Power Supplier (SMPS) module to generate a current of a power supply signal, the SMPS module comprising:
• a driver for controlling a plurality of switch transistors according to an input signal;
• a plurality of switch transistors for regulating a current amount under the control of the driver;
• and
• a filter for filtering a signal having passed through the switch transistors;
• and
• a linear regulator including a plurality of transistors and an amplifier for regulating a current amount generated by the transistors,
• wherein the linear regulator regulates the current amount generated by the transistors by at least one of generating a source current for supplementing an insufficient amount of the current generated by the SMPS module by using a first transistor from among the plurality of transistors and generating a sink current for eliminating an excessive amount of the current generated by the SMPS module by using a second transistor from among the plurality of transistors, and
• wherein the SMPS module generates the current of the power supply signal by selecting at least one of a plurality of power supplies, each of the power supplies having different voltages according to a voltage level of the input signal of the SMPS module.