Single cell rail-to-rail input/output operational amplifier
US6433637B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 23, 2001 |
| Grant date | Aug 13, 2002 |
| Priority date | — |
| Expiry date | Mar 23, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45644
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method and apparatus is directed to a rail-to-rail MOS amplifier that operates with a very low power supply. An input stage amplifier operates over rail-to-rail common-mode voltages. The input stage amplifier includes two differential input stages that steer current to loads in a class AB turnaround stage. The class AB turnaround stage converts the differential signals into a single signal that is driven into an output stage amplifier. The output stage amplifier includes level shifting buffer amplifiers that are arranged to bias a pair of MOS output transistors. Each level shifting buffer amplifier is arranged to bias a MOS transistor in a sub-threshold operating region such that the MOS transistor operates as a resistor. The MOS resistor works in conjunction with a MOS diode to provide an AB bias voltage to a gate of a respective one of the output transistors. The level shifting buffer amplifiers are also arranged such that the gate of each output transistor is selectively switched to a power supply voltage, providing maximum gate drive to the output transistor when the output transistor drives a maximum current to an external load. A single capacitor may be employed to provide …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.