论文部分内容阅读
本文论述了高频浅体声波(SBAW)晶体延迟线的设计和制造。为了避免低频体波源倍频后固有相位噪声的增大,就要求直接产生频率为千兆赫范围的信号。如果用一个体波晶体锁定千兆赫频率,就可改善其近载频相位噪声。本文所提到的延迟线采用近似AT和BT切晶体,因为AT切具有高的波速,而BT切则具有良好的温度稳定性。采用串联模型来选择设计参数。该模型利用窗口宽度,指数,波速及耦合常数来预测辐射电阻、电容和转换损耗。把该模型与传输损耗的实测数据结合起来考虑,就能准确地预测延迟线的总插入损耗。近来对该模型的仔细研究表明,在千兆赫频率上,插入损耗和Q值之间有着很好的折衷解决办法。用电子刻蚀法在有机玻璃保护层上做出0.4μm的图形。保护层一般是单层的。但也试验过多层方案。已经提出金属换能法的叉指是否灌封在晶体中的判断准则。通常金属叉指并不灌封在晶体中,器件仍具有低的插入损耗、高的Q值及良好的温度稳定性。AT切晶体的基波与五次泛音延迟线和BT切晶体的五次泛音延迟线均采用卸下(Lift—off)法制作。频率范围为3—5GHz。其最好的延迟线的插入损耗不到20,Q值大于2000。使用在高真空下冷焊的TO—8外壳还设计出了低耦合的封装。此延迟线不用有机材料,而是将其固定在一个无应力的不锈钢支架上。本文也给出了相应噪声和预老化数据。
This article discusses the design and manufacture of high-frequency, shallow-body acoustic wave (SBAW) crystal delay lines. In order to avoid the increase of the inherent phase noise after the low-frequency body wave source frequency doubling, it is required to directly generate the signal with the frequency in the gigahertz range. If a body-wave crystal is used to lock the gigahertz frequency, its near-carrier-phase noise can be improved. The delay lines mentioned in this article use approximation of AT and BT cut crystals because AT cuts have high wave speeds and BT cuts have good temperature stability. The series model is used to select the design parameters. The model uses the window width, index, wave speed and coupling constant to predict the radiation resistance, capacitance and conversion loss. Combining this model with the measured data of transmission loss can accurately predict the total insertion loss of the delay line. A careful study of the model recently shows that there is a good compromise between insertion loss and Q at gigahertz frequencies. 0.4μm pattern was made on the protective layer of organic glass by electronic etching method. Protective layer is generally a single layer. But also tested a number of programs. The criteria for judging whether or not the interdigital metal fingers are potted in a crystal have been proposed. Often metal fingers are not encapsulated in the crystal and the device still has low insertion loss, high Q and good temperature stability. The fundamental wave of AT cut crystal and the fifth overtone delay line of the fifth harmonic overtone and the BT cut crystal are made by the lift-off method. The frequency range is 3-5GHz. The best delay line insertion loss less than 20, Q value greater than 2000. The TO-8 housing, which is cold-welded under high vacuum, is also designed with a low-profile package. Instead of organic material, this delay line is attached to a stress-free stainless steel holder. This paper also gives the corresponding noise and pre-aging data.