A Low-Power Low-Phase-Noise VCO with Self-Adjusted Active Resistor

Junyi Sun, Chirn Chye Boon, Xi Zhu, Xiang Yi, Khanna Devrishi, Fanyi Meng

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


This letter presents a low-power low-phase-noise VCO with self-adjusted active resistor (SAAR). A pair of PMOS transistors is introduced between cross-coupled pairs and LC-tank, serving as the SAAR. When cross-coupled transistor resides in the saturation region, SAAR exhibits small resistance, enabling fast switching and suppressing flicker noise up-conversion to 1/f3 phase noise. Moreover, as cross-coupled transistor enters triode region, SAAR will adjust to larger resistance and prevent the small conducting resistance of the cross-coupled transistor degrading the quality factor of LC tank. Fabricated in a 65 nm CMOS technology, the proposed VCO demonstrates a tuning range of 5.07-6.35 GHz (22.4%) with only 0.42 mW power consumption at 0.6 V supply. The phase noise in the worst case is -40.8 dBc/Hz at 1 kHz and -111 dBc/Hz at 1 MHz, respectively.

Original languageEnglish
Article number7400947
Pages (from-to)201-203
Number of pages3
JournalIEEE Microwave and Wireless Components Letters
Issue number3
Publication statusPublished - 1 Mar 2016
Externally publishedYes


  • flicker noise
  • low-power
  • phase noise
  • self-adjusted active resistor (SAAR)


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