A 45GHz CMOS transmitter SoC with digitally-assisted power amplifiers for 64QAM efficiency improvement

A 45GHz 64QAM system-on-chip (SoC) CMOS transmitter with digitally-assisted power amplifiers (DAPA) is presented. The SoC includes a 7M gate ASIC with 9b reconfigurable symbol mapping, 8X upsampling, 161tap pulse shape filtering, IQ imbalance correction and DAPA envelope/time estimation. The ASIC feeds two 10b IQ current-steering DACs and active IQ modulator. A unique transformer splitting up converter drives eight parallel combined DAPAs. The chip is packaged in aluminum housing with WR22 outputs. A 64QAM signal achieves 1.8% EVM with 33dBc ACPR at 45GHz. The data rate is 450Mbps and the integrated output power exceeds -10dBm.