Ring oscillator circuit having improved frequency stability with respect to temperature, supply voltage, and semiconductor process variations
US5072197A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 3, 1991 |
| Grant date | Dec 10, 1991 |
| Priority date | — |
| Expiry date | Jan 3, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L1/00
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A compensation circuit (14) for a ring oscillator (12) having an odd plurality of series-connected CMOS inverter stages includes first and second P-channel transistors and a resistor. The first transistor (32) has a source coupled to VDD and a gate coupled to ground. The resistor (34) is coupled between the drain of the first transistor and ground. The second transistor (36) has a source coupled to VDD, a gate coupled to the drain of the first transistor, and a drain coupled to a supply node of each of the inverter stages of the ring oscillator for providing a supply voltage that is compensated with respect to voltage, temperature, and semiconductor processing variables. In operation, the conductivity of the first transistor inversely controls the conductivity of the second transistor that supplies a compensated power to the inverter stages. The compensated power controls the conductivity of the transistors in the ring oscillator and the corresponding frequency of oscillation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.