Terahertz CMOS frequency generator using linear superposition technique

Daquan Huang*, Tim R. Larocca, Mau-Chung Chang, Lorene Samoska, Andy Fung, Richard L. Campbell, Michael Andrews

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

103 Scopus citations


A low Terahertz (324 GHz) frequency generator is realized in 90 nm CMOS by linearly superimposing quadruple (N=4) phase shifted fundamental signals at one fourth of the output frequency (81 GHz). The developed technique minimizes the fundamental, second and third order harmonics without extra filtering and results in a high fundamental-to-4 th harmonic signal conversion ratio of 0.17 or {-}{15.4 dB}. The demonstrated prototype produces a calibrated {- }{46̃dBm} output power when biased at 1 V and 12 mA with 4 GHz tuning range and extrapolated phase noise of {- }{91̃dBc/Hz} at 10 MHz frequency offset. The linear superposition (LS) technique can be generalized for all even number cases ( N=2k, where k=1,2,3,4,\ldots ,n) with different tradeoffs in output power and frequency. As CMOS continues to scale, we anticipate the LS N=4 VCO to generate signals beyond 2 Terahertz by using 22 nm CMOS and produce output power up to {- }{1.5̃dBm} with 1.7% power added efficiency with an LS VCO + Class-B Power Amplifier cascaded circuit architecture.

Original languageEnglish
Article number4684629
Pages (from-to)2730-2738
Number of pages9
JournalIEEE Journal of Solid-State Circuits
Issue number12
StatePublished - 1 Dec 2008


  • CMOS Terahertz generator
  • DAC-to-RF conversion efficiency
  • Fundamental-to-fourth harmonic signal conversion ratio
  • Linear superposition (LS) circuit technique
  • Phase noise of terahertz CMOS signal generation
  • Terahertz signal generation

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