Accurate ultra-low current generator
US6657420B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 19, 2001 |
| Grant date | Dec 2, 2003 |
| Priority date | — |
| Expiry date | May 6, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05F1/575
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A method and apparatus provide for accurate low current generation using switched capacitor techniques. The current generator includes a reference voltage generator that provides a reference signal to a switched capacitor integrator. In one example, the reference circuit includes a switched capacitor divider. The switched capacitor integrator circuit produces a voltage ramp in response to the reference signal and other timing signals. The rate of the voltage ramp is proportional to the ratio of capacitors in the switched capacitor integrator and a clock frequency that is associated with the timing signals. A feedback circuit impresses the voltage ramp across an output capacitor circuit that has a very low capacitance value. The capacitor is arranged to differentiate the voltage ramp to produce an accurate low current. The switched capacitor design is suitable for integration in a monolithic integrated circuit. The integrator and the feedback stage are periodically reset.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.