Voltage Controlled Oscillator

Computing & Wireless : Hardware

Available for non-exclusive licensing


  • Earl Swartzlander, Jr., Ph.D. , Electrical and Computer Engineering
  • Moises Robinson , Xilinx
  • Marwan Hassoun , Xilinx
  • Shahriar Rokhbaz , Xilinx

Background/unmet need

Most digital electronic circuits require clocks to coordinate the processing of data. The clocks are often formed using phase-locked loops. Phase-locked loops require an oscillator (a basic source for the clock) that has a frequency that can be adjusted by means of a control voltage. Such oscillators are referred to as voltage controlled oscillators (or VCOs).

Invention Description

Most voltage controlled oscillators are implemented via ring oscillators, which consist of an odd number of inverting stages with the output of the last stage being fed into the first stage. This invention consists of a single-stage ring oscillator. It also includes the capability for both coarse and fine adjustment of the oscillator frequency.


  • Since only a single stage ring oscillator is required by this invention, less power is consumed than for multiple-stage ring oscillators.
  • The single-stage ring oscillator is capable of operating at higher frequencies than multiple-stage ring oscillators.
  • The invention is capable of oscillating over a wider range than conventional ring oscillator based VCOs.

Market potential/applications

All digital systems with multiple clocks that need to maintain a fixed frequency relationship (such as one clock is four times as fast as a second clock which is twice as fast as a third clock, etc.)

Development Stage

Proof of concept

IP Status