The methods of maintaining Low frequency stability in FBAR based cross-coupled VCO design

LETTER

Guoqiang Zhang, Abhay Kochhar, Keiji Yoshida, Shuji Tanaka, Kenya Hashimoto, Masayoshi Esashi, Ramesh K. Pokharel

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Keywords: film bulk acoustic resonator, cross-coupled architecture, low frequency instability, phase noise, VCO

JOURNAL FREE ACCESS

2013 Volume 10 Issue 12 Pages 20130296

DOI https://doi.org/10.1587/elex.10.20130296

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Abstract

In this letter, we propose the methods to mitigate low frequency instability in a film bulk acoustic resonator (FBAR) based cross-coupled voltage-controlled oscillator (FBAR-VCO). The first method employs a capacitor and while the other one employs a series inductor-capacitor. Using the post-layout simulation, a comparative study of the performances such as phase noise and figure of merit (FOM) of the designed FBAR-VCO is carried out. It is found that both the methods inhibit the low frequency instability successfully and the additional advantage of the second method is 2dB improvement of FOM. Compared to other published FBAR-VCOs, this work has very low phase noise, below -150dBc/Hz at 1MHz offset frequency, and much better FOM below -210dB.

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