A 300 GHz CMOS Transmitter with 32-QAM 17.5 Gb/s/ch Capability over Six Channels

Kosuke Katayama, Kyoya Takano, Shuhei Amakawa, Shinsuke Hara, Akifumi Kasamatsu, Koichi Mizuno, Kazuaki Takahashi, Takeshi Yoshida, Minoru Fujishima

Research output: Contribution to journalArticlepeer-review

97 Citations (Scopus)


A 300 GHz transmitter (TX) fabricated using a 40 nm CMOS process is presented. It achieves 17.5 Gb/s/ch 32-quadrature amplitude modulation (QAM) transmission over six 5 GHz-wide channels covering the frequency range from 275 to 305 GHz. With the unity-power-gain frequency fmax of the NMOS transistor being below 300 GHz, the TX adopts a power amplifier-less QAM-capable architecture employing a highly linear subharmonic mixer called a cubic mixer. It is based on and as compact as a tripler and enables the massive power combining necessary above fmax without undue layout complication. The frequency-dependent characteristics of the cubic mixer are studied, and it is shown that even higher data rates of up to 30 Gb/s are possible at certain frequencies, where the channel signal-to-noise ratio is high. The design and the operation of the power-splitting and power-combining circuits are also described in detail. The measurements reported herein were all made 'wired' via a WR3.4 waveguide.

Original languageEnglish
Article number7565498
Pages (from-to)3037-3048
Number of pages12
JournalIEEE Journal of Solid-State Circuits
Issue number12
Publication statusPublished - 2016 Dec
Externally publishedYes


  • Power combiner
  • power splitter
  • quadrature amplitude modulation (QAM)
  • subharmonic mixing
  • terahertz (THz) transmitter (TX)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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