![]() Figure 1a is a typical crystal-oscillator circuit using external capacitors and resistors. The resistors, moreover, provide the damping needed to prevent overdriving, which can permanently damage the crystal or resonator.įigure 1 shows two Pierce oscillator examples. For stable operation in such a design, the phase-shift compensation and gain control are provided by additional capacitors and resistors. Typically, a power-supply bypass capacitor is the only external component required with most silicon oscillators.Ĭrystal and ceramic resonator-based oscillators are most often implemented as Pierce oscillators, in which the crystal or resonator serves as a tuned element in the feedback of an inverting amplifier. Silicon oscillators, however, normally occupy the smallest space and do not require additional timing components. ![]() With their high Q values, crystals generally produce the lowest noise oscillator circuits, making them particularly well suited to systems requiring low baseband noise such as audio CODECs. The supply voltages for silicon oscillators typically range from 2.4V to 5.5V.Ĭlock noise is influenced by a number of sources including amplifier noise, power supply noise, board layout, and the intrinsic noise rejection (or 'Q') properties of the oscillating element. Microcontroller clock supply voltages typically range from 1V to 5.5V. By contrast, systems without external communications may function perfectly well with a clock-source accuracy of 5%, 10%, or even 20%.Ĭomparison Between Silicon Oscillators and Crystals or Ceramic Resonators ![]() High-speed USB, for example, requires a total clock accuracy of ☐.25%. Accuracy requirements are typically determined by the communications standards defined for an application. Silicon oscillators, moreover, do not require careful matching of timing components or board layout.Īpart from any environmental considerations in an application, the selection criteria for a clock source usually depend on four basic parameters: accuracy, supply voltage, size, and noise. Unlike crystal and ceramic resonator-based oscillators, silicon-based timing devices are relatively insensitive to vibration, shock, and electromagnetic interference (EMI) effects. It believes that the NKN-xLZT ceramic system in this work will become one of the most promising candidates for high-temperature capacitor devices.Silicon oscillators are a simple and effective solution for the majority of microcontroller (♜) clock needs. Therefore, the low loss tangent and high permittivity were still stabilized at the high temperature. The decrease of oxygen octahedron distortion induced a weak polarization, and the high resistance (9 × 10⁶ Ωcm at 400 ☌) greatly suppressed the long-term migration of defective ions in the ceramics. Additionally, the crystal structure distortion and conduction behaviors of the NKN-xLZT ceramics were systematically studied. A relative permittivity (ε’ = 1560 ± 15%) with low loss tangent over wide temperature range from 96 ☌ to 350 ☌ was obtained in the x = 0.02 ceramics. The NKN-xLZT ceramics with sub-micrometer grains (0.2–0.4 μm) were synthesized via a conventional solid-state sintering route. a novel (1-x)Na0.5K0.5NbO3- xLa(Zn0.5Ti0.5)O3 (NKN-xLZT) ceramics were chosen to meet the targets in this work. ![]() In order to increase the working temperature and relative permittivity. Nevertheless, conventional barium titanate-based capacitors show narrow operating temperature ranges owing to the low tetragonal-cubic phase transition temperature. Ceramic-based dielectrics are considered as the best candidates for high temperature capacitors because of their outstanding mechanical and electrical properties. ![]()
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