Here, we present a millimeter-wave (mm-Wave) broadband power amplifier (PA) with a common-mode (CM) stability improvement technique. Unlike conventional broadband PAs, which consider only the differential-mode (DM) stability, our proposed PA simultaneously enhances the DM stability and the CM stability. To ensure CM stability, a small resistor is first connected in series to a capacitor to reduce its Q factor; then, these components are attached in parallel at the center tap of the input balun to increase the CM path loss. Therefore, the stabilization of the PA can be improved over the entire frequency band to ensure a properly broadband work. Our proposed broadband PA with CM stability enhancement technique is finished in a commercial 65 nm CMOS process with a core area of 0.13 mm2. Adopting continuous-wave testing, the PA exhibits 56.3% 1-dB output 1-dB compression point power (OP1dB) fractional bandwidth and 3-dB small signal gain fractional bandwidth from 23 to 41 GHz that covers the whole Ka-band. At 28/39 GHz, the PA provides +14.8-/+14.1-dBm saturation output power (Psat), +12.4-/+12.0-dBmOP1dBand 29.8%/23.8% peak power added efficiency (PAE). The measured stability parameters indicate the proposed CM stability enhanced broadband PA is unconditionally stable over the entire frequency band. For a 100-MHz 1-CC 64-QAM signals (roll-off factor = 0.45 and PAPR = 7.1 dB), at a carrier frequency of 28 GHz, the PA demonstrates 8.6 dBm average output power (Pavg), 5% average power added efficiency (PAEavg), -32.4 dBc adjacent channel leakage ratio (ACLR) and -25.4 dB EVM. For a 400-MHz single-carrier 64-QAM signal, this proposed PA still provides 8.1-dBmPavgand 4.5%PAEavgwith a -34.2 dBc ACLR and -25.3 dB rms EVM at 28 GHz.

The rapid urbanization and development of modern cities increases the demand of the city's infrastructure networks. Particularly, a continuous expansion of electric network scale is required, which results in an increase of system capacitive current. For the arc suppression coil grounding system, increasing compensation capacity of arc suppression coil is necessary, especially when the single-phase earth fault occurs. And this could be realized by updating the master arc suppression coil. In this paper, a new approach is adopted which involve installing a distributed arc suppression coil to cooperate with the mater one. The compensation effect of distributed arc suppression coil is studied through establishing models of 10kV network system and distributed arc suppression coil with the software PSCAD/EMTDC. Different installation positions and compensation capacities are investigated. The results show that the use of the distributed arc suppression coil can markedly reduce the fault residual current into a controllable and reasonable range. Among four different installation positions, line terminal installation is relatively preferable. Besides, the proportion of distributed compensation capacity in total system compensation capacity should preferably be 45%, where residual current at the point of grounding fault always remain as less than 5A.