This paper presents a broadband efficient power amplifier (PA) targeting sub-6-GHz 5G base station applications. Due to the demanding requirements in both peak-to-average power ratio (PAPR) and bandwidth in 5G systems, we employ a combination of both load and supply modulation for efficiency enhancement. Active matching, implemented using an RF-input load-modulated balanced amplifier (LMBA) architecture, enables efficient octave-bandwidth operation. Supply modulation, which is carrier frequency agnostic, is then used to further extend the back-off efficiency. This paper focuses on a study of supply modulation strategies for the load-modulated PA using an efficient GaN eight-level discrete supply modulator. To overcome the bandwidth limitations associated with discrete-level switching, a commutation rate reduction (CRR) filter is applied in digital baseband and its effects are analyzed theoretically and experimentally. The supply-modulated LMBA is characterized across 1.8-3.8 GHz with 100-MHz, 10-dB PAPR signals. An output power of 34 dBm with average composite (total) PAE ranging from 22.4% to 43.9% across the band is demonstrated, with an ACLR of about -50 dBc after digital predistortion.
Cappello T., Pednekar P., Florian C., Cripps S., Popovic Z., Barton T.W. (2019). Supply- and Load-Modulated Balanced Amplifier for Efficient Broadband 5G Base Stations. IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, 67(7), 3122-3133 [10.1109/TMTT.2019.2915082].
Supply- and Load-Modulated Balanced Amplifier for Efficient Broadband 5G Base Stations
Florian C.;
2019
Abstract
This paper presents a broadband efficient power amplifier (PA) targeting sub-6-GHz 5G base station applications. Due to the demanding requirements in both peak-to-average power ratio (PAPR) and bandwidth in 5G systems, we employ a combination of both load and supply modulation for efficiency enhancement. Active matching, implemented using an RF-input load-modulated balanced amplifier (LMBA) architecture, enables efficient octave-bandwidth operation. Supply modulation, which is carrier frequency agnostic, is then used to further extend the back-off efficiency. This paper focuses on a study of supply modulation strategies for the load-modulated PA using an efficient GaN eight-level discrete supply modulator. To overcome the bandwidth limitations associated with discrete-level switching, a commutation rate reduction (CRR) filter is applied in digital baseband and its effects are analyzed theoretically and experimentally. The supply-modulated LMBA is characterized across 1.8-3.8 GHz with 100-MHz, 10-dB PAPR signals. An output power of 34 dBm with average composite (total) PAE ranging from 22.4% to 43.9% across the band is demonstrated, with an ACLR of about -50 dBc after digital predistortion.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
