Development of a concurrent dual-band switch-mode power amplifier based on current-switching class-D configuration

Abstract

It was recently shown that concurrent dualband class-A and -B power amplifiers have a maximum theoretical concurrent-mode (two simultaneous stimuli) drain efficiency of 25% and 62%, respectively, lower than their singlemode counterparts (one stimulus). This paper presents analysis demonstrating that by using current-switching class-D architecture, the concurrent-mode efficiency degradation can be theoretically reduced to zero and a drain efficiency of 100% can be achieved. This theory is then used to design, fabricate, and test a concurrent dual-band current-switching class-D power amplifier operating at 960 MHz and 1.51 GHz. The fabricated PA has a measured concurrent-mode drain efficiency of 46%, which is only 9.6% lower than the low-band single-mode (one stimulus) drain efficiency (55.6%) and only 2.2% lower than the high-band single-mode drain efficiency (48.2%). The corresponding measured concurrent-mode output power is 29.7 dBm, showing only 0.3 dB reduction from the single-mode output power of 30 dBm.

Fourier Analysis of Signal Waveforms in An Ideal Concurrent Dual-Band Class-D Power Amplifier

“…Non-contiguous carrier aggregation (CA) has been supported by LTE-Advanced [1] and is also a specification of 5G NR [2]. It has recently led researchers to look for concurrent multiband power amplifiers (PAs), which are capable of supporting multiple carrier frequencies simultaneously [3][4][5][6]. There are several challenges to designing concurrent multiband PAs that have been observed in the literature.…”

“…Chief among these problems are a reduced efficiency and output power when compared to their singleband counterparts [7]. Taking a page out of the book of singleband PA designs, researchers have recently demonstrated a switch-mode class-D configuration to obtain high efficiency out of a dual-band PA [4,8].…”

“…Even though the concurrent dual-band class-D PA has shown good performance empirically [4], it has not rendered well to symbolic analysis, compelling authors to curtail theory in lieu of direct numerical computation, as is often the case with complex PA designs [9]. On the other hand, an ideal single-band class-D PA can be analyzed using Fourier series with relative ease [10].…”