#OSCULATOR DEFINIITON PC#
An example is the clock oscillator in a PC that sets the speed of calculations. The clock signal is used to operate all the circuits in synchronism. The frequency determining element is usually a quartz crystal that vibrates at a precise frequency and is very stable. It is used as an accurate time and frequency source. Crystals come in a small metal package and are used to set the frequency in most oscillators today.Ī special type of oscillator is called a clock oscillator. It maintains its frequency very closely unlike RC or LC networks that can drift with temperature or change from vibration or other conditions. A crystal is a thin piece of quartz that can be made to vibrate at a very precise frequency. That circuit may be made up of RC, LC, or a crystal. The frequency of an oscillator is set by some frequency determining element or circuit. By varying the value of a DC input voltage, the frequency is changed. These are called voltage-controlled oscillators (VCOs). Some oscillators are tuned by an external voltage. You can often tune it by turning a knob that varies a capacitor or inductor to change the frequency. A tunable frequency oscillator is called a variable frequency oscillator. Most oscillators have a fixed frequency but there are oscillators whose frequency can be varied. The main specification of an oscillator is its output frequency. (A) Sine wave, (B) rectangular pulse, (C) voltage-controlled oscillator, and (D) crystal clock oscillator. Additionally, its board footprint, a 5-pin SOT-23 package and a single resistor, is notably small.įigure 4.15. Its accuracy and drift specifications fit between resonator-based types and typical RC oscillators. A new device, LTC1799, is also an RC type but fills the need for a simply applied, broadly tuneable, accurate oscillator. A problem with conventional RC oscillators is that considerable design effort is required to achieve good specifications.
Typical RC types have lower initial accuracy and increased drift but are easily tuned over broad ranges. Quartz crystals and ceramic resonators offer high initial accuracy and low drift but are essentially untuneable over any significant range. Commonly employed oscillators are resonant element based or resistor–capacitor (RC) types. Transducer circuitry, carrier-based amplifiers, sine wave formation, filters, interval generators, and data converters all utilize different forms of oscillators. The most obvious oscillator application is a clock source in digital systems. A substantial percentage of electronic apparatus utilizes oscillators, either as timekeeping references, clock sources, for excitation or other tasks. Oscillators are fundamental circuit building blocks. Jim Williams, in Analog Circuit Design, 2011 Publisher Summary