2.4 GHz 基板合成波導共振腔振盪器之設計與Q值和相位雜訊相關性分析

Abstract

本論文使用基板合成波導共振腔來設計一頻段於2.4 GHz振盪器。利用基板合成波導共振腔平面化結構與高附載品質因素的特性，我們可以低成本製作出具有低相位雜訊振盪器。 此外，在本篇論文之中，我們也進行品質因素對相位雜訊效應的檢驗。根據1966年由D. B. Leeson所提出的相位雜訊模型，其預估當諧振器的負載品質因素每增加一倍時，振盪器的相位雜訊將相對具有6 dB的衰減。由於品質因素取決於諧振器的板材損耗與匹配電路，因此我們可以在不同板材上製作振盪器以獲得具有不同品質因素的設計。製作在板材RO4003(QL=91.81)的設計，所量測的相位雜訊在偏移100kHz為-110.2 dBc/Hz，在偏移1MHz為-127 dBc/Hz；相對於在板材RO3003(QL=42.91)與FR4(QL=21.44)的設計，分別具有6dB與11dB的衰減。利用這些具有同架構但在不同板材的設計，我們可以在量測結果與由模型所計算出的預估值上得到相同的趨勢，因此，成功地驗證品質因素與相位雜訊的關係。

This thesis presents a design of 2.4 GHz oscillators by using substrate-integrated waveguide cavities. With the planar structure and high-Q characteristic of SIW cavity, we could design the low phase noise oscillator in low-cost production. Besides, the effect of Q-factor to phase noise is examined in this thesis. According to the phase noise model proposed by D.B. Leeson in 1966, it estimates about 6 dB reductions in phase noise as Q-value of resonator doubled. Since the Q-factor depends on the cavity substrate loss and matching conditions, we could design oscillators on different substrates with different Q-values of SIW cavity resonators. The measured phase noise of the design on RO4003 (QL=91.81) is approximated as -110.2 dBc/Hz at 100 kHz offset, and -127 dBc/Hz at 1 MHz offset with 6 dB reductions comparing to the design on RO3003 (QL=42.91) and 11 dB reductions comparing to the design on FR4 (QL=21.44). By using these oscillators in the same parallel feedback structure, we could obtain the same tendencies between measurements and computed values from the proposed model and thus verified the relation between Q-factor and phase noise.