Theory: oscillation frequency stabilization. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Beginner radio amateur

 Comments on the article

The requirements for the stability of the oscillation frequency of generators and radio transmitters are constantly increasing, which is associated with a large "load" of the air, narrowing the bandwidth of receivers, and the use of the most advanced methods for transmitting analog and digital information. The relative frequency instability of conventional LC oscillators with an oscillating circuit is about 0,01% and by special measures (thermostating, using quality parts) can be increased by an order of magnitude. This is not enough, but, fortunately, a simple and reliable way to improve frequency stability has long been known. It consists in the use of a quartz resonator.

A quartz plate, cut in a certain way from a crystal, has a piezoelectric effect: when it is deformed, charges appear on the surface. There is also an opposite effect: the application of stress to the surfaces of the plate causes its deformation. The plate has its own mechanical resonance, and its quality factor can reach tens and hundreds of thousands - values ​​that are unattainable in conventional circuits. In addition, the mechanical resonance frequency is very stable - it depends only on the size of the plate and is almost not subject to external influences.

A quartz resonator is similar in design to a capacitor - a quartz plate is placed between two plates, from which conclusions are drawn. The linings are now most often sprayed onto the surface of the plate. In electrical terms, a quartz resonator is similar to an oscillatory circuit, the diagram of which is shown in Fig. 53.

At the series resonance frequency fs, the reactance vanishes, and at the parallel resonance frequency fp it becomes infinite (if we neglect the small losses associated with the resistance r). The equivalent inductance of quartz is large (Henry units), and the series capacitance Cs is small (hundredths of a picofarad), while the parallel capacitance Cp can reach tens of picofarads (it is calculated using the usual formula for the capacitance of a flat capacitor in which quartz serves as a dielectric). As a result, the frequency difference between parallel and series resonances is about 0,1% of the resonant frequency.

In precision quartz oscillators, the series resonance frequency is used as the least susceptible to destabilizing factors, while in simpler oscillators it is more convenient to excite the oscillator at frequencies near parallel resonance, where the resistance of the quartz is inductive, due to which it successfully replaces the inductor.

A diagram of such a generator is shown in fig. 54.

A major disadvantage of quartz oscillators is the impossibility of frequency tuning. Only a small adjustment within fractions of a percent is permissible, for which the tuning capacitor C1 serves. Spontaneous frequency drift of such a generator can be as small as 1 Hz per 1 MHz (relative instability 10^-6).

Author: V.Polyakov, Moscow

See other articles Section Beginner radio amateur.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Traffic noise delays the growth of chicks 06.05.2024

The sounds that surround us in modern cities are becoming increasingly piercing. However, few people think about how this noise affects the animal world, especially such delicate creatures as chicks that have not yet hatched from their eggs. Recent research is shedding light on this issue, indicating serious consequences for their development and survival. Scientists have found that exposure of zebra diamondback chicks to traffic noise can cause serious disruption to their development. Experiments have shown that noise pollution can significantly delay their hatching, and those chicks that do emerge face a number of health-promoting problems. The researchers also found that the negative effects of noise pollution extend into the adult birds. Reduced chances of reproduction and decreased fertility indicate the long-term effects that traffic noise has on wildlife. The study results highlight the need ... >>

Wireless speaker Samsung Music Frame HW-LS60D 06.05.2024

In the world of modern audio technology, manufacturers strive not only for impeccable sound quality, but also for combining functionality with aesthetics. One of the latest innovative steps in this direction is the new Samsung Music Frame HW-LS60D wireless speaker system, presented at the 2024 World of Samsung event. The Samsung HW-LS60D is more than just a speaker system, it's the art of frame-style sound. The combination of a 6-speaker system with Dolby Atmos support and a stylish photo frame design makes this product the perfect addition to any interior. The new Samsung Music Frame features advanced technologies including Adaptive Audio that delivers clear dialogue at any volume level, and automatic room optimization for rich audio reproduction. With support for Spotify, Tidal Hi-Fi and Bluetooth 5.2 connections, as well as smart assistant integration, this speaker is ready to satisfy your ... >>

A New Way to Control and Manipulate Optical Signals 05.05.2024

The modern world of science and technology is developing rapidly, and every day new methods and technologies appear that open up new prospects for us in various fields. One such innovation is the development by German scientists of a new way to control optical signals, which could lead to significant progress in the field of photonics. Recent research has allowed German scientists to create a tunable waveplate inside a fused silica waveguide. This method, based on the use of a liquid crystal layer, allows one to effectively change the polarization of light passing through a waveguide. This technological breakthrough opens up new prospects for the development of compact and efficient photonic devices capable of processing large volumes of data. The electro-optical control of polarization provided by the new method could provide the basis for a new class of integrated photonic devices. This opens up great opportunities for ... >>

Random news from the Archive Wavy transistors 16.02.2006 Scientists at the University of Illinois have made harmonica-like transistors. To make semiconductor harmonicas, scientists from the University of Illinois (USA), led by Professor Yongan Huang, deposited ultra-thin strips of semiconductor devices from single-crystal silicon onto a standard silicon substrate. Then, using etching, they were cut off, obtaining ribbons 100 nm thick, and a sheet of stretched rubber was placed on top. Silicon strips stuck to it and separated from the substrate. When the rubber sheet shrunk, the result was a wavy surface similar to accordion bellows. Like a real accordion, it can be squeezed and stretched many times, and this does not affect the operation of semiconductor devices. "Expandable silicon diodes and transistors are just two examples of wavy electronic devices that can be made with our technology," says Yongan Huang. artificial human muscles or tissues".

Other interesting news:

▪ TV damages the brain

▪ Global Shutter CMOS image sensor with extended dynamic range

▪ The release of analog TVs is curtailing

▪ Power supplies Dark Power 12

▪ Processor Intel Core i9-13900KS

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Intercoms. Article selection

▪ article Secrets of the rubber motor. Tips for a modeller

▪ article How do snails walk? Detailed answer

▪ Chinese cabbage article. Legends, cultivation, methods of application

▪ article Spectrum of a musical signal. Part 8. Encyclopedia of radio electronics and electrical engineering

▪ article The simplest circuits of single-cycle converters. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024