A 273-301-GHz Amplifier With 21-dB Peak Gain in 65-nm Standard Bulk CMOS

• Published in: IEEE microwave and wireless components letters Vol. 29; no. 5; pp. 342 - 344
• Main Authors: Tokgoz, Korkut Kaan, Abdo, Ibrahim, Fujimura, Takuya, Pang, Jian, Kawano, Yoichi, Iwai, Taisuke, Kasamatsu, Akifumi, Watanabe, Issei, Okada, Kenichi
• Format: Journal Article
• Language: English
• Published: IEEE 01.05.2019
• Subjects: 300 GHz; amplifier; bulk CMOS; Capacitors; Gain; Layout; layout optimization; Logic gates; low-loss passives; Metals; positive feedback (PF); Resistance; subterahertz; Transistors
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2019.2908335

This letter presents a world-first 300-GHz amplifier in 65-nm standard bulk CMOS (1P9M GP). The amplifier has gain from 273 to 301 GHz, and the peak gain is 21 dB at 298 GHz. The amplifier has 16-stage positive-feedback common-source topology. The power consumption is 35.4 mW from a 1.2-V supply. Transistor (<inline-formula> <tex-math notation="LaTeX">1\,\,\mu \text{m}\,\,\times 8\,\,\mu \text{m} </tex-math></inline-formula>) layout is optimized for minimizing gate and channel resistance to increase gain corner frequency from 250 GHz (conventional design kit-based transistor measurement result) to 270 GHz, and <inline-formula> <tex-math notation="LaTeX">f_{\mathrm {max}} </tex-math></inline-formula> from around 300 GHz (design kit based) up to 317 GHz. Four transistor widths of 8, 10, 20, and <inline-formula> <tex-math notation="LaTeX">30~\mu \text{m} </tex-math></inline-formula> with the optimized layout are compared with the terms of <inline-formula> <tex-math notation="LaTeX">f_{\mathrm {max}} </tex-math></inline-formula> proving that the 8-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> width transistor has the highest <inline-formula> <tex-math notation="LaTeX">f_{\mathrm {max}} </tex-math></inline-formula> and hence used in the 300-GHz amplifier design. The dc-blocking capacitors are 10-fF finger-based design, which has lower loss than conventional MOM capacitors, since the fingers are formed on the top metal that is the thickest metal layer in the process.