page_title: Colpitts oscillator
section_title: Practical example
hierarchical_section_title: Colpitts oscillator / Overview / Practical example
context_page_description: A Colpitts oscillator, invented in 1918 by American engineer Edwin H. Colpitts, is one of a number of designs for LC oscillators, electronic oscillators that use a combination of inductors and capacitors to produce an oscillation at a certain frequency. The distinguishing feature of the Colpitts oscillator is that the feedback for the active device is taken from a voltage divider made of two capacitors in series across the inductor.
context_section_description: Fig. 3 shows a working example with component values. Instead of bipolar junction transistors, other active components such as field-effect transistors or vacuum tubes, capable of producing gain at the desired frequency, could be used.
  The capacitor at the base provides an AC path to ground for parasitic inductances that could lead to unwanted resonance at undesired frequencies. Selection of the base's biasing resistors is not trivial. Periodic oscillation starts for a critical bias current and with the variation of the bias current to a higher value chaotic oscillations are observed.
caption: Figure 3: Practical[dubious  – discuss] common-base Colpitts oscillator with an oscillation frequency of ~50 MHz