Patent attributes
The present invention is ripple cancellation circuitry used with a switching power supply, which provides direct current (DC) power via a DC power amplifier (PA) signal to an RF PA final stage. The DC PA signal includes a DC component and a power supply ripple component, which is generated as a result of the switching characteristics of the switching power supply and creates an output ripple in an RF output signal from the PA final stage. The ripple cancellation circuitry substantially cancels the output ripple by adding a ripple cancellation signal having a ripple component that is phase-shifted approximately 180 degrees from the output ripple to the RF output signal. The ripple cancellation circuitry uses a switching signal that is provided by the switching power supply to generate the ripple cancellation signal.
