Abstract: A radio system comprises a power source and a power amplifier circuit coupled to the power source on a power line. The radio system also comprises an active cancellation circuit. The active cancellation circuit comprises a bi-directional DC-DC converter. The active cancellation circuit is configured to cancel low-frequency emissions from the power amplifier circuit on the power line.

Abstract: A multiresonant DC to DC converter which operates at a substantially fixed frequency yet maintains relatively constant efficiency levels despite wide variations in input voltage. The multiresonant converter includes a first transistor switch in series with the DC voltage supply source and the load and a second transistor switch in parallel with the DC voltage supply source and the load. The switching action of the first transistor switch is controlled as a function of the supply voltage input to the converter while the duty factor of the second transistor switch is controlled in accordance with the output voltage of the converter.