Current-controlled p-channel transistor-based ring oscillator

Abstract

A current-controlled oscillator (ICO) circuit including an all p-channel transistor based ring oscillator, a first current mirroring stage, and a second current mirroring stage. The all p-channel transistor based ring oscillator, p-channel transistors in the input structure of each amplification stage, and metal lines in the ring and from the ring to the amplification stages over an n-well improve noise immunity and tolerance. The first current mirroring stage utilizes an input current to generate a first voltage controlling a series of differential delay cells connected in a ring topology that forms the ring oscillator. The second mirroring stage utilizes a precision current to generate a second voltage controlling at least one amplification stage, which converts corresponding delay cell output signals to a single-ended logic level signal compatible with external circuitry needs. Each amplification stages utilizes the second control voltage to create a similar or ratioed copy of the precision current flowing in each amplification stage. A second embodiment of the ICO is also included, which operates at a lower frequency, thus higher bandwidth, than that of the first embodiment.