A spurious emission reduction technique for power amplifiers using frequency hopping DC-DC converters

Abstract

This paper presents a spurious emission suppression technique for RF power amplifiers using frequency-hopping DC-DC converters. The frequency-hopping technique changes the switching frequency of the DC-DC converter dynamically and reduces the peak spur created by using a DC-DC converter with a radio frequency power amplifier. The use of this technique can also reduce the size of the external passive components used for reducing the ripple voltage of the DC-DC converter, which creates the radio frequency spurs. A prototype system using a cellular band power amplifier operating at 836.5 MHz and a commercial DC-DC converter was built to verify this technique. Measurement results show by frequency-hopping between eight frequencies, the maximum radio frequency spur can be reduced by more than 11 dB.