Doherty Amplifier Design Based on Asymmetric Configuration Scheme

Abstract

A practical Doherty amplifier design method has been developed based on an asymmetric configuration scheme. By embedding a load modulation function into matching circuits of a carrier amplifier (CA) and a peaking amplifier (PA) in the Doherty amplifier, an issue of the Doherty amplifier design is boiled down to the CA and PA matching circuit design. The method can be applied to transistors with unknown parasitic elements if optimum termination impedance conditions for the transistor are obtained from a source-/load-pull technique in simulation or measurement. The design method was applied to GaN HEMT Doherty amplifier MMICs. The fabricated 4.5-GHz-band GaN HEMT Doherty amplifier MMIC exhibited a maximum drain efficiency of 66% and a maximum power-added efficiency (PAE) of 62% at 4.1 GHz, with a saturation output power of 36 dBm. In addition, PAE of 50% was achieved at 4.1 GHz on a 7.2-dB output backoff (OBO) condition. The fabricated 8.5-GHz-band GaN HEMT Doherty amplifier MMIC exhibited a maximum drain efficiency of 53% and a maximum PAE of 44% at 8.6 GHz, with a saturation output power of 36 dBm. In addition, PAE of 35% was achieved at 8.6 GHz on a 6.7-dB (OBO). And, the fabricated 12-GHz-band GaN HEMT Doherty amplifier MMIC exhibited a maximum drain efficiency of 57% and a maximum PAE of 52% at 12.4 GHz, with a saturation output power of 34 dBm. In addition, PAE of 32% was achieved at 12.4 GHz on a 9.5-dB (OBO) condition.

A 24-30GHz Power Amplifier with >20-dBm Psat and <0.1-dB AM-AM Distortion for 5G Applications in 130-nm SiGe BiCMOS

“…For this reason, SiGe BiC-MOS and CMOS PAs have been proposed as preferred for this application [27], [28], [31]- [33]. In addition, while circuit topologies such as Doherty and outphasing are highly efficient as described in [34], [35], they tend to be large in size, so miniaturised PAs are preferable.…”

Class-E Power Amplifier with Improved PAE Bandwidth Using Double CRLH TL Stub for Harmonic Tuning

“…For this reason, microstrip lines (MSLs), instead of lumped-elements, are commonly used for designing harmonic tuning circuits (HTCs) for such high frequencies. (The exceptions are PAs designed in MMIC technology, in which spiral inductors and MIM capacitors with good high frequency characteristics are available [4]. )…”