Royer oscillator
Encyclopedia
A Royer oscillator is an electronic oscillator
which has the advantages of simplicity, low component count, rectangle
waveforms and easy transformer
isolation. It was first described by George H. Royer in December 1954 in Electrical Manufacturing.
transformer with a primary winding, a feedback winding and (optionally) a secondary winding. The primary winding is centre-tapped, with each half driven by a transistor
collector. The feedback winding couples a small amount of the transformer flux back in to the transistor
bases to generate the oscillations. The oscillation frequency is determined by maximum magnetic flux density power supply voltage and inductance of the primary winding.
of an LCD display. CCFL inverter
s produce a sinusoidal waveform for good efficiency, which is necessary for good battery life on portable equipment.
Electronic oscillator
An electronic oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave. They are widely used in innumerable electronic devices...
which has the advantages of simplicity, low component count, rectangle
Rectangle
In Euclidean plane geometry, a rectangle is any quadrilateral with four right angles. The term "oblong" is occasionally used to refer to a non-square rectangle...
waveforms and easy transformer
Transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...
isolation. It was first described by George H. Royer in December 1954 in Electrical Manufacturing.
Circuit description
The circuitry consists of a saturable-coreSaturable reactor
A saturable reactor in electrical engineering is a special form of inductor where the magnetic core can be deliberately saturated by means of a direct electric current in a control winding...
transformer with a primary winding, a feedback winding and (optionally) a secondary winding. The primary winding is centre-tapped, with each half driven by a transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
collector. The feedback winding couples a small amount of the transformer flux back in to the transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
bases to generate the oscillations. The oscillation frequency is determined by maximum magnetic flux density power supply voltage and inductance of the primary winding.
Applications
The Royer oscillator circuit was an old circuit, and it was being used for past DC-AC inverter. There is collector resonance circuit which often be mistaken be called with the Royer oscillator circuit. The inventor of the collector resonance type oscillator is not George H. Royer but another inventor. As for the oldest invention, it is known as the Bell Telephone Laboratories's invention. These are being used for drive the cold cathode fluorescent lamp (CCFL) backlightBacklight
A backlight is a form of illumination used in liquid crystal displays . As LCDs do not produce light themselves , they need illumination to produce a visible image...
of an LCD display. CCFL inverter
CCFL inverter
A CCFL inverter is a device for providing drive power to a Cold Cathode Fluorescent Lamp . CCFLs are often used as inexpensive light units in electrical devices.-Applications:#widely used in backlights for LCDs...
s produce a sinusoidal waveform for good efficiency, which is necessary for good battery life on portable equipment.
External links
- Theory of operation
- HVwiki
- "Who was Royer and what did he invent?" (Appendix K) in Jim WilliamsJim Williams (analog designer)James M. "Jim" Williams was an analog circuit designer and technical author who worked for the Massachusetts Institute of Technology , Philbrick, National Semiconductor and Linear Technology Corporation...
, "A fourth generation of LCD backlight technology: Component and measurement improvements refine performance", Linear Technology Application Note 65, November 1995.