Method and circuit for comparator-less generation of ramped voltage having controlled maximum amplitude
US6339349B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Feb 2, 2000 |
| Grant date | Jan 15, 2002 |
| Priority date | — |
| Expiry date | Feb 2, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K4/502
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A circuit for generating a ramped voltage having controlled maximum amplitude (e.g., for use in a switching controller), and a method for generating such a ramped voltage without use of a comparator. The ramped voltage is a voltage developed across a periodically charged and discharged capacitor, or optionally a level-shifted version of such voltage. Preferably, a ring oscillator generates a clock signal (without use of a comparator) for use in controlling the periodic charging and discharging of the capacitor, and a feedback loop generates a supplemental charging current for the capacitor in response to feedback indicative of the ramped output voltage. Preferably, the ring oscillator is a current-starved ring oscillator biased by a zero temperature coefficient bias current source, and the feedback loop includes a sample-adjust-hold circuit which samples the ramped output voltage shortly before the capacitor discharges, generates an adjustment voltage indicative of the difference between a reference voltage and the sampled output voltage, and holds the adjustment voltage for use in the next charging cycle. Preferably, a current mirror generates the supplemental charging current in …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.