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使用高次泛音体声波谐振器(HBAR),可能研制出直接工作在微波频率的低相位噪声倍频微波源。最近,已研制出一个L波段的低噪声源,它能提供约以5MHz为间隔的信号,并能得到与低频石英晶体稳定和倍频的微波源相同的相位噪声抑制度,高次泛音体声波谐振器(HBAR)直接倍频到微波源需要少量硬件,以达到用任何其它方法得到倍频微波源所具有的相同的相位噪声抑制度。稳定的工作是通过利用钇铝石榴石(YAG)、蓝宝石、铌酸锂式铝酸锂等晶体的高次泛音谐振来达到的。它们的固有损耗表明,其潜在Q值近似为石英晶体的十倍。已制成的这种谐振器的频率高达10GHz。对1.5GHz频段的压缩模式,已在几个样品中得到50,000以上的有载Q值。这些谐振器由其晶片上渡漠换能器组成。单纯的反射被限制在换能器之下区域内。晶体牢牢地被装在外壳中,以尽量减小外部振动对频率稳定度的影响。测量振动灵敏度的情况在一篇参考文献中简述。此倍频微波源包括一个用自动频率控制(AFC)回路稳定的低噪声压控振荡器(VCO)。在自动频率控制(AFC)鉴频器中,高次泛音体声波谐振器是决定频率的元件。测量的相位噪声与估计的性能很一致。本文提供了噪声特性的详细情况。用附加的数字控制电路将压控振荡器予调到高次泛音体声波谐振器(HBAR)的任一次响应上,可以很容易地实现倍频。因此,用最少的硬件得到了低相位噪声用电子方法控制的倍频源。
Using high-order transonic acoustic resonators (HBARs), it is possible to develop low-phase-noise multiplier microwave sources that operate directly at microwave frequencies. Recently, a low-noise L-band noise source has been developed which provides signals at intervals of about 5 MHz and achieves the same phase noise suppression as low frequency quartz crystal stabilized and multiplied frequency microwave sources. High-order overtone sound waves Direct multiplication of the resonator (HBAR) to the microwave source requires a small amount of hardware to achieve the same degree of suppression of phase noise achieved by the multiplying frequency microwave source by any other method. Stable work is achieved by utilizing the high order overtone resonance of crystals such as yttrium aluminum garnet (YAG), sapphire, lithium niobate lithium aluminate and the like. Their intrinsic loss shows that their potential Q value is approximately ten times that of quartz crystals. Such resonators have been made with frequencies up to 10 GHz. For the compression mode in the 1.5 GHz band, an on-load Q of 50,000 or more has been obtained in several samples. These resonators consist of an over-the-air transducer on their wafer. Simple reflections are limited to the area under the transducer. The crystal is held firmly in the enclosure to minimize the effect of external vibration on frequency stability. The measurement of vibration sensitivity is briefly described in a reference. The frequency multiplier microwave source includes a low noise voltage controlled oscillator (VCO) stabilized with an automatic frequency control (AFC) loop. In automatic frequency control (AFC) frequency discriminators, high-order transonic acoustic resonators are components that determine the frequency. The measured phase noise is in good agreement with the estimated performance. This article provides details of the noise characteristics. Frequency doubling can be easily achieved by using additional digital control circuitry to apply the voltage-controlled oscillator to any of the high-order harmonic body acoustic wave resonators (HBARs). Therefore, electronically controlled multiplier sources with low phase noise are obtained with minimal hardware.