Efficient GaN Doherty PAs with digital predistortion (DPD)
may provide the required margin, but these devices are still in
development for mmWave applications. But it won't be long
before we see an all-digital beamforming solution. Several
developments will make it a reality:
• Next-generation digital-to-analog and analog-to-digital
converters that save power
• Advances in mmWave CMOS transceivers
• Increased levels of small-signal integration
Integrated FEM with GaN Doherty PA and Switch-LNA
Hybrid approach
An alternative is hybrid beamforming, where the precoding and combining are done in both baseband and RF front-end
module (FEM) areas. By reducing the total number of RF chains and analog-to-digital and digital-to-analog converters, hybrid
beamforming achieves similar performance to digital beamforming while saving power and reducing complexity.
Another advantage of the hybrid approach is the ability to meet both a suburban fixed or limited scan range (<20º) and dense
urban deployments with wide scan ranges in both azimuth (~120°) and elevation (~90°).
Hybrid Beamforming Active Antenna Systems (ASS) Block Diagram
| 8 |
Key Features:
• Tx linear power: 24dBm
@ 4% EVM
• Rx NF: 4.2dB including
switch loss
•
High gain: 23dB (Tx),
Key Features:
• Tx linear power: 24dBm
@ 4% EVM
• Rx NF: 4.2dB including
switch loss
• Compact 4.5 x 6.0mm
footprint
QPF4006 37-40.5GHz GaN Front End
Module (PA + LNA + Switch)
QPF4005 37-40.5GHz GaN Dual Channel
FEM (PA + LNA + Switch)
18dB (Rx)
mouser.com/qorvo-qpf4006-module
mouser.com/qorvo-qpf4005-module
The bottom line: All-digital and hybrid approaches both have advantages and disadvantages. We believe the hybrid approach
is more appealing and doable today, but new products on the horizon could make the all-digital approach equally appealing in
the future.
