Abstract-A 37.5-mW 8-dBm-EIRP 15.5 $^{circ}$-HPBW 338-GHz Terahertz Transmitter Using SoP Heterogeneous System Integration

Li, C.-H. 
Department of Electrical Engineering, National Central University, Jhongli, Taiwan 
Chao, T.-Y. ; Lai, C.-W. ; Chen, W.-C. ; Ko, C.-L. ; Kuo, C.-N. ; Cheng, Y.T. ; Kuo, M.-C. ; Chang, D.-C.

A low-cost terahertz transmitter is proposed by using system-on-package (SoP) heterogeneous system integration. A signal source in 40-nm CMOS is integrated with an antenna array on a Benzocyclobutene carrier through a broadband low-loss terahertz interconnect. The signal source adopting triple-push oscillator topology is able to produce a differential output without any additional balun circuit. Hence, the power consumption and the chip area can be reduced. The antenna array containing 50 patch antennas is differentially excited to give simulated directivity, efficiency, and antenna gain as high as 22.6 dB, 88%, and 22 dBi, respectively, at 335 GHz. The terahertz interconnect employs a resonator coupling technique to provide low-loss and broadband performance while occupying a small area. Measured results show that the proposed terahertz transmitter can work at 338.4 GHz with equivalent isotropically radiated power (EIRP) of 8.0 dBm while consuming only 37.5 mW from a 1-V supply. The measured half-power beam-width can be as narrow as 15.5$^{circ}$ . The EIRP can be further raised to 9.5 dBm as the supply $V_{ DD}$ is increased to 1.3 V. The CMOS chip only occupies an area as small as 0.028 ${hbox {mm}}^{2}$. All of the design efforts enable the proposed terahertz transmitter to feature in small form factor, low power dissipation, low cost, and high performance. To the best of the authors' knowledge, this is the most compact, lowest power, lowest cost, and high-performance SoP-based terahertz transmitter reported thus far.

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