Oscillators

An oscillator is the electronic circuit found within a device. It produces an output signal with consistent and continuous amplitude and a specific frequency. Given that an oscillator will generate waveforms at generally frequencies, it is also commonly referred to as a waveform generator for electronics. An electronic oscillator is often found in digital watches and clocks, computers and many complex electronic systems. The AC signals at specific frequencies generated by an electronic oscillator are widely used for radio or television signal transmission.

The main role of an electronic oscillator is to convert direct current (DC) power to an alternating current (AC) signal for use in operating an electronic device. The form of the signal produced by an electronic oscillator is typically a sine or square wave from a periodic electronic signal. When DC power is connected to the electronic circuit, this is sufficient input for the oscillator to produce an AC signal at a specific frequency with the help of a transistor or a vacuum tube. On the other hand, an amplifier, which works in conjunction with an oscillator, requires an external input to generate a signal.

The two major types of electronic oscillators based on the types of waveforms that they generate are linear and nonlinear oscillators. The linear electronic oscillators are also called harmonic oscillators, which produce a sinusoidal output. The nonlinear electronic oscillators are also called relaxation oscillators and produce a non-sinusoidal output. In terms of the types of components of an oscillator, the major classifications are RC, LC and crystal. Oscillators are also characterized by the level of frequency that they generate, which ranges from low to high.

A harmonic oscillator is a linear oscillator that is most commonly used as an electronic amplifier. They use the feedback resistor including electronic amplifiers in order to increase negative resistance. This type of harmonic oscillators produces a sinusoidal output, which is a continuous wave as part of a smooth periodic oscillation.

A feedback oscillator is a type of harmonic oscillator that is generally characterized according to the particular type of frequency selective filter used in its feedback loop. The categories of feedback oscillators include RC, LC and crystal oscillators. These types of oscillators incorporate a feedback network sufficient to satisfy the requirements for oscillations within the oscillator circuit.

Unlike the feedback oscillator, a negative-resistance oscillator does not include a feedback network. The typical range of a negative-resistance oscillator is at or above the microwave range because a feedback oscillator generally cannot function as reliably at these higher frequencies due to the phase shift in their feedback path. The resonant circuit of a negative-resistance oscillator connects across an electronic device with negative differential resistance. Power is supplied to the resonant circuit from a DC signal. Ultimately, oscillations at the desired resonant frequency are produced when the internal loss resistance of the electronic circuit is canceled out by the negative resistance.

A voltage-controlled oscillator (VCO) is designed so that the device’s set frequency can be changed within a specified range by varying the current or voltage applied to the oscillator. This type of oscillator is most commonly found in phase-locked loops, which allow the frequency of the VCO to be set in conjunction with another oscillator. When used in the transmission and receipt of radio signals, a VCO usually has a varactor diode added to the resonator or oscillator. An increase in the input voltage for a VCO results in a sped-up charging rate of the capacitor.

The crystal oscillator is a mainstay in the design and manufacturing of a broad range of consumer electronic products. For a crystal oscillator, the specific frequencies produced can vary from 32.768kHz to over 150MHz. At higher frequencies, a crystal oscillator is more likely to be used for the transmission of radio signals. Crystal oscillators are commonly found in many of Suntsu’s high-quality electronic devices and products because of their properties for maintaining accurate and stable frequencies despite external changes. In terms of mechanical operations, the mechanical vibrations of the quartz crystal resonator determine the specific frequency that is generated from the crystal oscillator.

A surface acoustic wave (SAW) oscillator is essential for producing the radio signals that are required for cellphones. What makes a SAW oscillator distinct from other forms of oscillators is that they rely on acoustic waves from the surface of a material for the processing of signals. In a SAW oscillator, the input transducer converts the electric signal into acoustic waves. The waves are converted again into signals by an output transducer after traveling through a solid propagation medium.

The differences between crystal vs. oscillator options without quartz crystal are expressed in the function of the end device, with crystal oscillators being the popular choice for many devices that require a precise and stable frequency. Crystal oscillator circuits are ubiquitous with top-notch and reliable performance in electronic devices, which is why they are so widely incorporated into products sold by Suntsu. They rely on the piezoelectric effect of quartz crystals to help keep electronic devices working properly and efficiently over their lifespan. The application of an AC signal to a quartz crystal causes it to vibrate, which produces a specific signal output. The resonant frequency of a quartz oscillator circuit experiences only slight variations due to changes in external temperatures or over the lifespan of the quartz crystal oscillator.

Microelectromechanical system (MEMS) oscillators are specifically used within timing devices. The MEMS resonators within the oscillator are what help set the desired frequencies, which tend to be much higher in MEMS oscillators than for other electronic devices. MEMS oscillators are considered a cutting-edge innovation from quartz crystal oscillators and have been commonly incorporated into commercial devices since 2006. They boast improved resistance to mechanical stresses and variations in external temperatures, which increases the stability of their frequencies.

A Colpitts crystal oscillator relies on a combination of inductors and capacitors to generate and maintain its continuous oscillation at the desired frequency level. What distinguishes the Colpitts oscillator is the fact that its voltage divider consists of two capacitors that operate in series resonance.

A Pierce crystal oscillator is an electronic oscillator that is derived from the Colpitts crystal oscillator. Almost all of the oscillators found in digital IC clock oscillators are of the Pierce variety. This is because the composition of this clock oscillator makes it a fairly simple oscillator circuit in terms of the parts required for its manufacture. It contains only one digital inverter and resistor as well as two capacitors and the quartz crystal. One of the reasons why Suntsu is able to provide such high-quality and top-performing electronic devices at such reasonable price points is that the manufacturing costs of this highly effective type of oscillator are significantly less than the cost of more material-intensive oscillators and electronic circuits.

A complementary metal-oxide semiconductor logic (CMOS) crystal oscillator circuit is especially useful for clock recovery, frequency synthesis, phase-locked loop (PLL), synthesizing, system references, clock translation and multiplexing. CMOS technology is used to design IC, and quartz crystal is used as the source clock. This type of crystal oscillator features a controlled rise (output waveforms changing from a low voltage level to a much higher voltage level) and fall (output waveforms reverting back to a low voltage level from a higher voltage level) times thanks to the high-speed CMOS, and the waveform is a rectangular shape.

In almost all microprocessors, there are two oscillator pins, OSC1 and OSC2, that attach to an oscillator circuit, which produces square wave pulses and helps determine the device’s frequency based on the vibrations of the activated quartz crystal. That specific device frequency is how the device’s processor receives the signals and information that it needs to function.

An oscillator has the capacity to run a long list of electronic devices that all depend on the stability of a specific frequency to work as expected. Some of the most common applications of oscillators include quartz watches, radio signal transmitters, audio systems, video systems, computers, inverters, metal detectors, microprocessors, water meter, telecommunication, based station, repeater, alarms, rubidium oscillator atomic clocks and lighting systems.

Oscillator circuits are self-sustaining in that they produce a periodic waveform at a constant rate and at a stable frequency. The losses in the feedback resonator circuit of an oscillator are overcome with an inductor or capacitor and from the application of a DC signal to the resonator at a precise frequency level. Because the oscillator circuit functions as an amplifier to produce an output frequency from positive feedback, it does not require an input signal to produce the desired frequency.

An oscillator at a resonant frequency is also sometimes called a tuned circuit. This occurs when the capacitive and inductive reactance of the oscillator circuit are the same, which means that the resistance of the circuit opposes the current’s flow. As a result, the current remains in phase with the circuit’s voltage without producing any phase shift. At a resonant frequency, the application of an oscillating force to the circuit allows for oscillations at a higher amplitude as compared to the resulting oscillations from the same level of force at non-resonant frequencies.

The oscillator frequency value is typically assessed and measured in Hertz (Hz) from a formula that divides the wavelength into the velocity. This tracks the oscillator waveform output in the number of oscillation cycles per second. The desired frequency value of an oscillator depends on its particular purpose and will bet set in the manufacturing process of the oscillator.

A feedback resistor sets the bias of the oscillator circuit and determines its stability. A feedback resistor is also called an Rƒ. In order for a feedback resistor in an oscillator to produce negative feedback, it feeds back part of the output signal to the negative terminal of the amplifier.