What is Royer Oscillator : Working and Its Applications

As we know that there are various types of oscillators but the Royer oscillator is one kind of oscillator. It is invented by the scientist G H Royer in the year 1954. As the name suggests, the name of this oscillator is taken from the scientist name ‘Royal’ who invented this oscillator. We have seen different components that can be taking part in the oscillator like an inductor, capacitor, crystal, etc. Here this oscillator uses a transformer at the output level to generate the signals like undistorted and continues. The specialty of this oscillator is it can generate the output waves in the form of a square and rectangular shape. In this article, we will discuss what is Royer oscillator, circuit diagram, and its applications.

What is the Royer Oscillator?

We can define the Royer oscillator like; it is one type of electronic oscillator which generates stable oscillations in the form of two shapes like square and rectangular at the required resonance frequency by using a transformer. The resonant Royer type oscillator will produce the output oscillations in the form of sine waves. This oscillator comes under the relaxation oscillator segment.


Royer Oscillator Circuit

Coming to the Royer oscillator circuit design, the input to the circuit is a 12V dc voltage source and the two transistors are named as Q1 and Q2. And it has a center-tapped transformer. Here the usage of the center-tapped transformer in the oscillator is to forward the voltage through a dielectric medium from the two transistors output which is Q1 and Q2.


Here the Q1 and Q2 transistors are not switched on at the same time because the supply voltage is not applied to the same time for both transistors and each transistor showing slightly different characteristics with other transistors and Q point also different for each transistor. Choosing the primary and secondary windings of the center-tapped transformer plays an important role to get the oscillations at the desired resonance frequency.

Royer Oscillator Circuit Operation

“Whenever the input voltage applied to the Q1 and Q2, transistor Q1 will turn ON more time than Q2. And Q1 enters into a saturation region while the other transistor Q2 will be in cut off state for some portion of the input voltage. Later, Q1 will be entering into the cut off region and Q2 will turn ON and gives the output. This process continues and gives the output. So whatever the output comes from the Q1 and Q2 will be forward to the output port through secondary windings of the center-tapped transformer in the form of the magnetic field.”


Now, we will discuss the few  Royer oscillator applications. They are:

  • These oscillators are used in DC to AC inverter circuits.
  • In flyback drivers these oscillators are useful.
  • Applicable in switching power supplies.
  • These oscillators are used in wireless transmission devices.

Thus, Royer oscillators are one type of relaxation oscillator. And by using the center-tapped transformer in the circuit it can able to generate the maximum frequency of oscillations at the desired frequency. And this oscillator is low cost and minimum size compare to other oscillator circuits. And the bulkiness of the circuit also minimized by the number of turns of the center-tapped transformer. There is a high preference given to these oscillators in the research processes of wireless power transmission. And need to analyze the effect of the transistors on the output with different conditions.