High-efficiency envelope tracking systems and methods for radio frequency power amplifiers
View Patent ↗Envelope tracking (ET) methods and systems for controlling the delivery of power to radio frequency power amplifiers (RFPAs). An exemplary ET system includes an RFPA and a wide bandwidth capable and power efficient envelope modulator that includes a first power supplying apparatus and a second power supplying apparatus. The first power supplying apparatus includes a switch-mode converter and a regulator. The first mode converter is operable to dynamically step down a fixed power supply voltage according to amplitude variations in an envelope signal received by the regulator, and use the resulting dynamic power supply signal to power the regulator. The second power supplying apparatus is connected in parallel with the first power supplying apparatus. Depending on a power of an output signal to be generated at an output of the power amplifier, power is supplied to the power amplifier from either or both of the first and second power supplying apparatuses.
1. An envelope modulator apparatus for generating a dynamic power supply signal, comprising:
a first switch-mode converter having a power supply input configured to receive a direct current (DC) power supply voltage, a switch control input configured to receive a first switch control signal, and an output configured to provide a dynamic power supply signal;
a regulator having an envelope signal input configured to receive an envelope signal, a power supply input configured to receive the dynamic power supply signal from said first switch-mode converter, and an output configured to supply current to a load; and
a second switch-mode converter having a power supply input configured to receive said DC power supply voltage, a switch control input configured to receive a second switch control signal, and an output configured to provide current to said load.
2. The envelope modulator apparatus of claim 1 wherein said first switch control signal includes signal characteristics relating to amplitude variations in said envelope signal, and the first switch-mode converter is configured to generate said dynamic power supply signal so that it generally tracks amplitude variations in said envelope signal.
3. The envelope modulator apparatus of claim 2 wherein said regulator comprises a linear regulator and said first switch-mode converter is configured to generate said dynamic power supply signal so that at any given time the dynamic power supply signal has a magnitude no higher than necessary to keep the linear regulator operating in its active region.
4. The envelope modulator apparatus of claim 1 wherein the first switch-mode converter and regulator are configured such that when the DC power supply voltage is coupled to the power supply input of said first switch-mode converter an amount of the DC voltage that is dropped across the first switch-mode converter compared to an amount of the DC voltage that is dropped across the regulator is dependent on signal characteristics contained in said first switch control signal.
5. The envelope modulator apparatus of claim 4 wherein the signal characteristics of said first switch control signal include signal characteristics relating to amplitude variations in said envelope signal.