Theory: frequency synthesizers. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Beginner radio amateur
Comments on the article
The desire to combine the possibility of tuning with high frequency stability led to the development of frequency synthesizers - devices that make it possible to obtain a whole grid of frequencies switched by choice from one highly stable one. Fine-grid synthesizers turned out to be a good replacement for smoothly tunable oscillators, through 100, 10 or even 1 Hz. They are successfully used in radio communication equipment.
The direct synthesis method involves multiplication and division, as well as addition and subtraction of frequencies to obtain the desired value. The method is quite complicated and requires a large number of multipliers, dividers and frequency converters with appropriate filters to attenuate side frequencies. It is easier to implement an indirect synthesis method based on the use of a phase locked loop (PLL) system. The block diagram of the simplest synthesizer based on this principle is shown in fig. 55. Such synthesizers are already widely used in household equipment: radios, car radios, televisions and radio stations in the "civilian" band 27 MHz (CB).
The frequency of the reference quartz oscillator (KG) is divided to obtain a "reference" frequency fop, equal to the required frequency grid step (9 kHz - in the LW and MW bands, 5 kHz - on KB and 10 kHz - on CB). The frequency of a controlled LC-or even RC-oscillator (UG) with low stability is also divided to approximately the same value. After comparing the signals with the reference frequency in the frequency-phase detector (PFD), a DC error signal is generated, which, through the low-pass filter, adjusts the frequency of the VG until the frequencies and phases of the signals at the PFD inputs are completely matched. This results in fo = mfop = (m/n)fop . The frequency of the controlled oscillator acquires the stability of a quartz one.
Synthesizers made on a single chip are widely used at present, and in the coming years we should expect their even greater distribution.
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:
Artificial leather for touch emulation
15.04.2024
In a modern technology world where distance is becoming increasingly commonplace, maintaining connection and a sense of closeness is important. Recent developments in artificial skin by German scientists from Saarland University represent a new era in virtual interactions. German researchers from Saarland University have developed ultra-thin films that can transmit the sensation of touch over a distance. This cutting-edge technology provides new opportunities for virtual communication, especially for those who find themselves far from their loved ones. The ultra-thin films developed by the researchers, just 50 micrometers thick, can be integrated into textiles and worn like a second skin. These films act as sensors that recognize tactile signals from mom or dad, and as actuators that transmit these movements to the baby. Parents' touch to the fabric activates sensors that react to pressure and deform the ultra-thin film. This ... >>
Petgugu Global cat litter
15.04.2024
Taking care of pets can often be a challenge, especially when it comes to keeping your home clean. A new interesting solution from the Petgugu Global startup has been presented, which will make life easier for cat owners and help them keep their home perfectly clean and tidy. Startup Petgugu Global has unveiled a unique cat toilet that can automatically flush feces, keeping your home clean and fresh. This innovative device is equipped with various smart sensors that monitor your pet's toilet activity and activate to automatically clean after use. The device connects to the sewer system and ensures efficient waste removal without the need for intervention from the owner. Additionally, the toilet has a large flushable storage capacity, making it ideal for multi-cat households. The Petgugu cat litter bowl is designed for use with water-soluble litters and offers a range of additional ... >>
The attractiveness of caring men
14.04.2024
The stereotype that women prefer "bad boys" has long been widespread. However, recent research conducted by British scientists from Monash University offers a new perspective on this issue. They looked at how women responded to men's emotional responsibility and willingness to help others. The study's findings could change our understanding of what makes men attractive to women. A study conducted by scientists from Monash University leads to new findings about men's attractiveness to women. In the experiment, women were shown photographs of men with brief stories about their behavior in various situations, including their reaction to an encounter with a homeless person. Some of the men ignored the homeless man, while others helped him, such as buying him food. A study found that men who showed empathy and kindness were more attractive to women compared to men who showed empathy and kindness. ... >>
| Random news from the Archive MAX30205 - medical digital temperature sensor
21.07.2017
The new MAX3025 digital sensor from Maxim Integrated measures human body temperature with an accuracy of 0,1°C over a temperature range of 37...39°C. The sensor will find application in medical devices, devices for sports and fitness.
A feature of the sensor is a 16-bit sigma-delta ADC, which allows you to register a temperature change of four thousandths of a degree.
The chip has an I2C interface with bus blocking protection. With address selection, up to 2 sensors can operate on a single I32C bus. In addition to direct temperature measurement, the MAX3025 contains a temperature comparator that signals on a separate line the fact that the temperature exceeds the set values.
The output of the built-in comparator is implemented as an open drain; it can also operate in the interrupt signal generation mode. In this case, the output value is fixed before the read operation of any register is performed on the I2C bus. The MAX30205 operates from 2,7V to 3,6V with a peak current draw of less than 600µA.
You can use the MAX30205EVSYS# demo kit to get familiar with the capabilities of the new sensor. It allows you to display the temperature value on the PC. The MAX30205 evaluation GUI software is used to display all sensor parameters.
|
Other interesting news:
▪ Airplane powered by steam jet
▪ Rapid recovery of valuable metals from old batteries
▪ Taste of soda and champagne
▪ The liver was taken out, repaired, inserted back
▪ electric car
News feed of science and technology, new electronics
Interesting materials of the Free Technical Library:
▪ section of the site Home workshop. Article selection
▪ article A bullet is a fool, a bayonet is a good fellow. Popular expression
▪ Article Who first discovered that the Earth is round? Detailed answer
▪ article Spanish golden root. Legends, cultivation, methods of application
▪ article Three-phase current is very simple. Encyclopedia of radio electronics and electrical engineering
▪ article Commutation of hand power tools. Encyclopedia of radio electronics and electrical engineering
Leave your comment on this article:
All languages of this page
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua
2000-2024
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese