Very Linear and Low-Noise Ka/Ku-Band Voltage Controlled Oscillators

Tsuneo TOKUMITSU  Osamu BABA  Kiyoshi KAJII  

IEICE TRANSACTIONS on Electronics   Vol.E85-C   No.12   pp.2008-2014
Publication Date: 2002/12/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Low-Distortion,High-Power,High-Efficiency Active Device and Circuit Technology)
voltage controlled oscillator,  linear frequency,  low-noise,  varactor,  

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A simple and practical methodology to make microwave voltage-controlled oscillators (VCOs) very linear is presented. Incorporating a very short microstrip line ( λg/4) for varactor's bias feed, the C-V curve was shifted by a constant -Δ C and performed a capacitance tailored nearly proportional to VCONT-2. This modification featured very linear VCO implementation at no expense of housing and phase noise performance. Ka- and Ku-band VCOs fabricated with this new technique exhibited a constant tuning sensitivity in a wide control voltage range (2-10 V). The phase noise level at 100 kHz offset was as low as -107 dBc/Hz for a 13 GHz-band VCO and better than -85 dBc/Hz for a 38 GHz-band VCO, due to combination of capacitor-coupled high-Q resonator and multiplier. This technology is very effective for quasi-millimeter-wave and millimeter-wave FM/FSK modulation and FMCW radar applications.