Patent ID: 7391275
Filing Date: 2008-06-24
Classification: H03K,H03L

Abstract:
1. A ring oscillator, comprising: a) an inverter chain comprised of a plurality of inverters connected in series including a first inverter at a first end of said inverter chain and a last inverter at a second end of said inverter chain opposite said first end, each of said inverters having a single input and a single output; b) a tank comprising an inductor, a capacitor, an input tank node coupled to the output of said last inverter, and an output tank node coupled to the input of said first inverter; and c) a trip point circuit coupled between said tank and said inverter chain, said trip-point circuit configured to maintain a low logic signal at the input of said first inverter when a voltage potential at said output tank node is below a predetermined level; wherein said trip-point circuit comprises a first diode chain consisting of a first plurality of diodes connected in series and a second diode chain consisting of a second plurality of diodes connected in series, said first diode chain being connected to said second diode chain at a junction diode node, wherein: a first diode node at a first end of said first diode chain is connected to a first power rail and said junction diode node is at a second end of said first diode chain opposite said first end of said first diode chain; a second diode node at a first end of said second diode chain is connected to a second power rail and said junction diode node is at a second end of said second diode chain opposite said first end of said second diode chain; and said output tank node is coupled to said junction diode node.