Embedded voltage controlled oscillator with minimum sensitivity to process and supply
US5847616A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 12, 1996 |
| Grant date | Dec 8, 1998 |
| Priority date | — |
| Expiry date | Dec 12, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03B2201/02
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
The present invention provides a voltage controlled oscillator with improved noise immunity and minimized variation due to manufacturing process, power supply and operating temperature changes. The voltage controlled oscillator consists of fully differential connected ring oscillator that includes a plurality of differentially connected delay elements. The ring oscillator responds to a control current signal for controlling the frequency of oscillation. A voltage to current converter converts the input tuning voltage to an output current for the controlling of the ring oscillator. The delay element consists of two source coupled P-channel transistors connected to a current source. The drains of the P-channel transistors are each connected to a voltage controlled impedance that changes the delay characteristics of the delay element in response to the input tuning voltage. A voltage reference generator provides the reference voltage necessary to determine the amplitude out of the delay element and is insensitive to variations due to manufacturing process, power supply, and operating temperature. A fully differential comparator provides symmetrical loading for the ring oscillator and …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.