Electrical engineering

Physics

Topology (electrical circuits)

Bandwidth (computing)

Wideband

CMOS

Modulation (music)

Engineering

Amplifier

Acoustics

RF power amplifier

Electronic engineering

Doherty amplifier

Reconfigurability

Computer science

Telecommunications

IEEE Transactions on Circuits and Systems I Regular Papers

This article introduces a novel high-order load modulation power amplifier (PA) architecture, i.e., continuous-mode hybrid asymmetric load modulated balanced amplifier (H-ALMBA). The two sub-amplifiers (BA1 and BA2) of the balanced topology in an LMBA are set as peaking amplifiers with different thresholds when cooperating with the control amplifier (CA) as the carrier, forming a hybrid load modulation behavior between Doherty and ALMBA. Compared to standard LMBA, the proposed H-ALMBA has a three-way load modulation with CA, BA1 and BA2 through proper amplitude control and phase alignment. Thus, this new mode offers extended power back-off range and enhanced back-off efficiency without suffering from difficulty and complexity in wideband design as imposed on three-way Doherty PAs. Based on comprehensive theoretical derivation and analysis, the proposed H-ALMBA is designed and implemented using commercial GaN transistors and wideband quadrature couplers. Moreover, the continuous-mode matching is applied to the carrier amplifier achieving a maximized wideband efficiency at power back-off. This is the first time that continuous mode and ALMBA have been used in combination, and very satisfactory results have been achieved, exhibiting the highest 10-dB OBO drain efficiency (DE) ever reported for wideband load-modulation PAs. The developed prototype experimentally demonstrates wide bandwidth from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.7 - 3.0$ </tex-math></inline-formula> GHz. The measurement exhibits an efficiency of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$63 - 81\%$ </tex-math></inline-formula> at peak output power, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$51 - 62\%$ </tex-math></inline-formula> for 5-dB OBO, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50 - 66\%$ </tex-math></inline-formula> for 10-dB OBO within the design bandwidth. When stimulated by a 20-MHz long term evolution (LTE) signal with 10.5-dB peak to average power ratio (PAPR), a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50 - 55\%$ </tex-math></inline-formula> average efficiency is measured over the entire bandwidth at an average output power around 32 dBm.

Continuous-Mode Hybrid Asymmetrical Load- Modulated Balanced Amplifier With Three-Way Modulation and Multi-Band Reconfigurability