Characterization of Concurrent Dual-Band Power Amplifiers Using a Dual Two-Tone Excitation Signal

• Published in: IEEE transactions on instrumentation and measurement 2015-10, Vol.64 (10), p.2781-2791
• Main Authors: Amin, Shoaib, Van Moer, Wendy, Handel, Peter, Ronnow, Daniel
• Format: Article
• Language: English
• Subjects: Amplifier distortion; characterization; Concurrent dual-band; cross modulation (CM); digital predistortion (DPD); DPD; Dual band; Electrical Engineering; Elektro- och systemteknik; Frequency-domain analysis; intermodulation (IM); Kernel; linearization; MIMO; multiple input multiple output (MIMO); nonlinear distortion; power amplifier; power amplifier (PA); Radio frequency; Transmitters
• ISSN: 0018-9456; 1557-9662; 1557-9662
• DOI: 10.1109/TIM.2015.2427731

A method to characterize the memory effects in a nonlinear concurrent dual-band transmitter is presented. It is an extension of the conventional two-tone test for power amplifiers to concurrent dual-band transmitters. The output signal of a concurrent dual-band transmitter is affected not only by intermodulation (IM) products but also by cross-modulation (CM) products. In one frequency band, the transmitter is excited by a two-tone signal which frequency separation is swept. In the second band, the transmitter is concurrently excited by another two-tone signal with slightly wider frequency separation. The frequency difference of the two signals is fixed during the frequency sweep. The two-tone test is made at different power levels. The upper and lower third-order IM and CM products are measured. The asymmetry between the upper and lower third-order IM and CM products are measures of the transmitter's memory effects. The measurement results show that the memory effects are more dominant in the third-order IM products than in the CM products. An error analysis and system calibration was performed and measurement results for two different devices are presented.