{"id":2422,"date":"2022-09-15T09:46:30","date_gmt":"2022-09-15T07:46:30","guid":{"rendered":"https:\/\/www.jauch.com\/blog\/?p=2422"},"modified":"2022-09-15T09:46:31","modified_gmt":"2022-09-15T07:46:31","slug":"quartz-crystals-and-oscillators-in-the-digitalization-trend","status":"publish","type":"post","link":"https:\/\/www.jauch.com\/blog\/en\/quartz-crystals-and-oscillators-in-the-digitalization-trend\/","title":{"rendered":"Quartz Crystals and Oscillators in the Digitalization Trend"},"content":{"rendered":"\n

For several years now the term \u2018Internet of Things\u2019 has been in common parlance.\nDevices that are part of the \u2018IoT\u2019 can communicate with each other wirelessly.\nThis is generally achieved using current standards such as WiFi, Bluetooth,\nZigbee, and 5G. The Internet of Things also changes the requirements placed on\nthe devices themselves. Today every smartphone is a connection node to other\ndevices. Smart Home applications and the Smart Watch on the wrist are just two\nof numerous examples. <\/p>\n\n\n\n

For all this to work smoothly, however, every component must be matched to the requirements of the wireless environment. This is also true for the tiny quartz crystals and oscillators that provide the clock signal in many electronic applications. So the question arises: what needs to be taken into account in the use of quartz crystals and oscillators in IoT applications?<\/p>\n\n\n\n

Increasingly small products require ever-smaller components<\/strong><\/h2>\n\n\n\n
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In recent years the availability of ever-smaller, battery-powered applications and wearables has grown sharply, notably in the consumer electronics sector. The products themselves, and thus also the circuit boards and components within them, are growing ever smaller. This trend is referred to as \u2018miniaturization\u2019. And for many products, including those of major IC manufacturers, no end is in sight for this trend, and this has implications for other components \u2013 including our quartz crystals and oscillators <\/p>\n<\/div><\/div>\n\n\n\n

As a consequence of this, changes are occurring to the\nrequirements placed on the housing and specifications of passive components \u2013\nwhich also have to be ever smaller. There are also advantages here; on the one\nhand, less raw material is required, which is good for the environment. On the\nother, the costs for packaging, transportation, and storage are reduced. <\/p>\n\n\n\n

One challenge faced by this trend is however the\nphysical limitation in respect of the frequency itself. To obtain a low\nfrequency of oscillation, the development process begins with a thick piece of\nquartz, whereas a higher frequency is obtained from a thinner crystal. The\nratio of surface area to thickness, meanwhile, must not fall below a certain\nvalue, otherwise the electrical parameters become unfavorable. Conversely, this\nmeans that with very small sizes, low frequencies (i.e. with thick crystals)\ncannot be generated effectively. This limitation primarily affects quartz\ncrystals and not quartz oscillators, as the latter contain an IC that can generally\ndivide the frequency down. As a consequence, oscillators have a wider scope of\npossibilities in regard to frequency. Additionally, some oscillators can also\nachieve significantly higher frequencies because the IC can multiply up the\nnatural frequency of the crystal.<\/p>\n\n\n\n

As a rule, quartz crystals are operated in what is known as a \u2018Pierce circuit\u2019. The illustration of the basic circuit elements shows that this consists essentially of two parts.<\/p>\n\n\n\n

\"Darstellung
Schematic of a Pierce circuit<\/em><\/figcaption><\/figure><\/div>\n\n\n\n

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These are the resonance\nloop, in which the original oscillation takes place, and the feedback loop that\nexcites the circuit into oscillation and then feeds in energy to compensate for\nlosses in the circuit.
\nThe quartz crystal in the resonance loop ensures that the oscillation occurs\nonly at its resonant frequency since it provides its best quality only at this\nfrequency.<\/p>\n\n\n\n

Reliable initiation of oscillation with a minimum of\nenergy<\/strong><\/h2>\n\n\n\n

Many small battery-powered devices are based on\n\u2018system-on-chip\u2019 (SoC) components. In these applications, power consumption is\na crucial factor. Yet low power consumption is often achieved today by using a\nlow operating voltage. This in turn has a negative effect on the reliability of\noscillation of the quartz circuit. To compensate for this negative effect, the\ndeveloper must pay particular attention to the choice of components and the\nbest possible matching of the circuit. <\/p>\n\n\n\n

To compensate for the negative impacts on the oscillation safety factor posed by smaller components and the low supply voltage, a reduced nominal load capacitance for the crystal is often selected. A circuit with a smaller CL<\/sub> can often also be used with weaker driver stages and still achieve acceptable oscillation reliability levels. During the matching process in the laboratory, the developer examines the frequency accuracy, oscillation safety factor and the output from the crystal to ensure a high level of operational reliability in the field. Jauch Quartz GmbH offers these analyses to its clients in order to provide support to developers working with these tasks.<\/p>\n\n\n\n

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\"Produktmanagerin
Oscillation safety factor, frequency accuracy and output from the crystal are analyzed during a circuit analysis. <\/em><\/figcaption><\/figure><\/div>\n\n\n\n

Highest frequency accuracy for wireless applications<\/strong><\/h2>\n\n\n\n

A major requirement for quartz crystals in wireless applications is naturally their frequency accuracy. Circuits are normally assigned radio wavelengths in narrow frequency bands. To prevent interference from other frequencies and also to enable connections over longer ranges, it is important that any wandering from the nominal frequency is kept to a minimum. In Bluetooth, for example, the maximum permitted frequency deviation is \u00b1 40 parts per million (ppm). This limit must not be exceeded at any point during the entire lifetime of the application under any circumstances. To ensure this, the developer must estimate all possible influences using a worst-case calculation, thus, in particular:<\/p>\n\n\n\n