2.7 A wideband 28GHz power amplifier supporting 8×100MHz carrier aggregation for 5G in 40nm CMOS

To meet rising demand, broadband-cellular-data providers are racing to deploy fifth generation (5G) mm-wave technology, e.g., rollout of some 28GHz-band services is intended in 2017 in the USA with ∼5/1Gb/s downlink/uplink targets. Even with 64-QAM signaling, this translates to an RF bandwidth (RFBW) as large as ∼800MHz. With ∼100m cells and a dense network of 5G access points (APs), potential manufacturing volumes make low-cost CMOS technology attractive for both user equipment (UE) and AP devices. However, the poor Pout and linearity of CMOS power amplifiers (PAs) are a bottleneck, as ∼10dB back-off is typical for meeting error-vector-magnitude (EVM) specifications. This limits communication range and PA power added efficiency (PAE), with wider RFBWs accentuating these issues further. On the other hand, sufficient element counts in the envisaged 5G phased-array modules can overcome path loss despite low Pout per PA, e.g., by combining RFICs in an AP. CMOS PAs with wideband linearity/PAE can therefore enable economical UE/AP devices to deliver 5G data-rates.