A Differential Amplifier with Enhanced Linearity of Average Power Region Using Dynamic Cross-Coupled Capacitor for 5G NR-U

This letter presents a differential power amplifier (PA) with high saturated output power and efficiency for 5G NR-U, and a proposed dynamic cross-coupled capacitor leads to a linearity improvement of the average output power region. The 4-way differential PA is implemented in a 2-µm InGaP/GaAs HBT process and on an 8-layer printed circuit board which renders a high turn ratio with a low insertion loss of the transformer. The PA consistently achieves a gain of 29.5 dB, a saturated output power of 36.05 dBm, and a power added efficiency (PAE) of 40.4% with collector voltage of 5.5 V over 5.15–5.925 GHz under continuous-wave signal. The linearity of the proposed PA is tested with 20 MHz 51 RB NR signal having a peak-to-average power ratio (PAPR) of 10.7 dB and achieves average output power of 27.18 dBm with PAE of 16.8% in E-UTRA ACLR condition.