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The microwave power transfer (MPT) system requires a massive Tx array for building a focused radio wave to efficiently transfer power to the Rx. Beamforming IC is one of the core elements for the massive Tx array. This paper presents a 5.8 GHz 4-channel beamforming Tx IC based on a CMOS process. The beamforming Tx IC includes a resistive 4-way power splitter, 5-bit differential phase shifters, drive amplifiers, and power amplifiers. Each channel is designed to transmit a power of no less than 100 mW. To verify the Tx IC, a 16-channel beamforming Tx module based on 16 patch antennas and four 4-channel Tx ICs was designed. The module also includes a PLL, a frequency doubler, and a 4-way Wilkinson power divider. MPT experiments to verify the beamforming IC and module were carried out using the implemented 16-channel Tx module at 5.8 GHz. Received power levels of 13 dBm and 2.1 dBm were achieved at distances of 0.4 and 1.4 m, respectively. The results are almost similar to the values acquired from the calculation using the Friis equation. INDEX TERMSMicrowave power transfer, massive Tx array, beamforming, complementary metal-oxidesemiconductor (CMOS), Tx IC.

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To investigate the relationship between headache and sleep by evaluating sleep quality, daytime sleepiness, and specific features related to sleep-disordered breathing (SDB).Methods: One hundred one subjects with headache and 118 healthy controls were enrolled. To collect various information on headache attacks, headache group completed self-reported questionnaire about the characteristics of headache attacks and the migraine disability assessment (MIDAS) questionnaire. The subjective quality of sleep was evaluated in all of the subjects using the Pittsburgh sleep quality index (PSQI) and Epworth sleepiness scale (ESS). In addition, the following specific features of sleep were evaluated in 28 subjects selected randomly from each group: apnea-hypopnea index (AHI), prevalence of SDB, nocturnal oxygen saturation (SaO 2 ), and oxygen desaturation index (ODI) as measured using a portable monitoring device. Results:The global PSQI and the prevalence of poor sleeping (global PSQI >5), ESS scores and the prevalence of daytime sleepiness (ESS score >10) were significantly higher in the headache group (both p<0.0001, respectively). The mean scores on the numerical rating scale and the MIDAS were significantly higher in the poor-sleeper group than in the good-sleeper group (p=0.0347 and p=0.0016, respectively). The global PQSI and prevalence of daytime sleepiness were significantly higher in the chronic-headache group than in the acute-headache group (p=0.0003 and p=0.0312, respectively). Conclusions:There is a significant association between headache and sleep. Especially, severity and chronicity of headache were significantly associated with sleep quality and daytime sleepiness.

This paper presents a generalized expression of the modified load networks (MLNs) for Doherty power amplifiers (DPAs) with an extended output power back-off (OBO) range. Based on the analysis using this new expression, a new circuit structure generally applicable to any combination of the multiple MLNs is proposed. The load network has a simple structure including impedance matching circuits and offset lines for the carrier and peaking amplifiers. A design procedure for the proposed load network is presented. A DPA using any optimized combination of the multiple MLNs can be easily designed using the proposed load network. For verification, a GaN-HEMT symmetrical DPA based on a combination of the virtual open-stub (VOS) and out-phased current combining (OCC) methods was designed and implemented for the frequency band of 3.4 -3.7 GHz. The reversed uneven power splitting method is adopted in the design for higher power gain. Using the 5G New Radio (NR) signal with a peak-to average power ratio (PAPR) of 7.9 dB and a signal bandwidth of 100 MHz, the proposed DPA exhibited DE of 55.3 -60.9% with a power gain of 11.9 -12.7 dB at an average output power of 33.7 dBm. An adjacent channel leakage power ratio (ACLR) of -42.6 --44.8 dBc was achieved at the average power level by using a digital predistortion (DPD) technique across the band.INDEX TERMS Doherty power amplifier, extended output power back-off, modified load network, virtual open stub, out-phased current combining, complex combining load, GaN-HEMT.