The effect of MOSFET second-order nonlinearity on active inductor-based oscillators

• Main Authors: A'ain, Abu Khari, Ler, Chun Lee, Kordesch, Albert Victor
• Format: Book Section
• Language: English
• Published: Institute of Electrical and Electronics Engineering (IEEE) 2007
• Subjects: TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://eprints.utm.my/id/eprint/9604/1/AbuKhariA%27ain2007_TheEffectOfMOSFETSecond.pdf; http://eprints.utm.my/id/eprint/9604/; http://dx.doi.org/10.1109/APACE.2007.4603974
• Institution: Universiti Teknologi Malaysia

Second-order nonlinearity of the MOSFET has significant impact on active inductor (AI) based oscillators, regardless of whether they are single-ended or differential. By using Taylor series expansion, this paper shows that second-order nonlinearity of the MOSFET will cause a shift in the DC biasing of an AI-based oscillator, depending on oscillation amplitude. The DC bias shift results in a change of the transistor transconductance and parasitic components from their original value, which will affect the oscillator resonance frequency. This explains why a small-signal S-parameter simulation is not sufficient to accurately predict the oscillation frequency and tuning range of AI-based oscillators, even at moderate oscillation amplitudes.