Square Wave Oscillators

The following op-amp circuit is a type of relaxation oscillator that produces a square-wave output. The operation of this circuit relies on the RC time constant for the charging and discharging of the capacitor. During circuit start-up, the voltage at the capacitor is at ground. Because the capacitor connects to the inverting terminal of the op-amp, as the negative terminal of the op-amp gets to or slightly below ground, the op-amp output goes high. From that point, the capacitor voltage rises up as a function of the RC time constant. As the voltage rises to the non-inverting terminal, the op-amp output goes low and the RC circuit discharges with the RC time constant. The waveform below demonstrates the capacitor voltage as well as the op-amp's square wave output.


20th Annual
Microchip MASTERs Conference 2016
Register now - Deadline: July 29

JW Marriott Desert Ridge Resort-Phoenix, AZ

© 2016 Microchip Technology, Inc.
Information contained on this site regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights.