Phase-&-amplitude CMOS controller to optimise Doherty amplifiers

June 11, 2015 // By Graham Prophet
Having previously outlined their proposed architecture, Peregrine Semiconductor has recently announced availability of its first UltraCMOS MPAC product: the PE46120 Monolithic Phase and Amplitude Controller (MPAC) is designed to optimise RF performance and implement phase-tuning in the 1.8 to 2.2 GHz frequency range.

PE46120 integrates a 90-degree hybrid splitter, phase shifters, digital step attenuator and a digital serial interface on a single die, for optimising dual-path dynamically load-modulated amplifier architectures such as Doherty power amplifiers, the monolithic RF controller offers high linearity, high isolation, high power handling and maximum phase-tuning flexibility compared to multi-chip, gallium arsenide-based solutions.

The UltraCMOS PE46120 is designed for the LTE and LTE-A wireless-infrastructure transceiver market. This product’s 1.8 to 2.2 GHz range is ideally suited to enhance system performance, lower bill of material (BOM) costs, increase reliability and provide maximum tuning flexibility for Doherty amplifier architectures found in wireless infrastructure applications— such as macrocells, microcells and picocells.

When used for Doherty amplifier optimisation, the PE46120 claims performance advantages in power added efficiency, linearity across the frequency range, Doherty bandwidth through better matching and increased effectiveness of the digital pre-distortion (DPD) loop. This MPAC product reduces BOM costs by improving the overall yield of expensive symmetric or asymmetric Doherty power amplifier assemblies. With uniformity and repeatability between transceiver paths, the PE46120 increases system reliability and increases transceiver yield. The monolithic controller can be used in either laterally diffused metal oxide semiconductor (LDMOS) or gallium nitride (GaN) Doherty amplifiers and can be programmed remotely through the digital interface to accommodate varying field requirements. This gives engineers the flexibility to adjust the phase and amplitude in real-time for operational and environmental factors.

“Doherty amplifiers remain strong as the power amplifier architecture of choice for today’s macrocell transceivers,” says Herman Hugo, global head of marketing and application engineering for RF power at Infineon Technologies . “As Infineon continues to develop leading- edge products that are customized for optimal performance in the overall system, the Peregrine Semiconductor MPAC product family offers RF performance and phase-tuning flexibility that will play a key role in Doherty amplifier optimisation, yield and uniformity.”

Because – Peregrine says – the PE46120 is based on UltraCMOS technology, it delivers