60GHz帯自己注入型NRDガイドガン発振器のQファクタ解析

摘要

Designing Q-factors of oscillator circuits is a key technology to realize frequency-stabilized oscillators; in particular; millimeter-wave oscillators because the phase noise tends to be degraded in millimeter-wave frequencies compared with that in centimeter frequencies due to performance of semi-conductor devices. Having this fact in mind; Q factors of NRD guide Gunn oscillator in free running and self-injection locking conditions were calculated by using the oscillator model including the Gunn device. Although the Q-factor in free running condition was lowered to be about 10; it was increased to be 150 by applying the self-injection technique. By using the calculated Q-factors; oscillation spectrums were evaluated. Agreement between the calculated and measured oscillation spectrums was quite satisfactory; and thus the validity of the presented analysis was confirmed.%ミリ波帯では半導体デバイスの性質上、利用する発振器の位相雑音がセンチ波帯と比べて劣化することから、安定度の高い発振器の実現のためにはQファクタの解析が重要になる。そこで60GHz帯NRDガイドガン発振器の、自走時び自己注入同期時のQファクタを、ガンダイオード素子を含めたモデルを用いて、大平の理論より導出した。その結果自走時のQファクタは10程度と低いが、無負荷Qが4000の誘電体共振器で自己注入同期を行った場合、そのQファクタは150と高く設定できることが明らかになった。またこれらのQファクタを用いて自走、及び自己注入同期発振器の発振スペクトラムを計算し、実験値と比較したところ、理論と実験は良好に一致し、本論で示したQファクタ解析の妥当性が確認された。