System and method for optimal biasing of a telescopic cascode operational transconductance amplifier (OTA)
US6362688B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 26, 2000 |
| Grant date | Mar 26, 2002 |
| Priority date | — |
| Expiry date | Apr 26, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45732
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A system and method of biasing a telescopic cascode operational transconductance amplifier is provided to prevent or reduce the likelihood that the inputs to the amplifier do exceed the input common mode voltage range for the amplifier. The system and method provides a bias control circuit for the differential input transistors and tail current transistor of the operational amplifier such that their respective Vds−Vdsat is maintained substantially constant. To accomplish this, the biasing system and method uses a bandgap voltage source that typically produces a highly stable voltage that is substantially temperature and process invariant. The bandgap voltage source is used to generate bias voltages applied to the gates and drains of the differential input transistors that maintains their and the tail current transistor's Vds−Vdsat substantially constant. There are several advantages of the system and method for biasing a telescopic cascode OTA. First, by keeping Vds−Vdsat substantially constant for the tail current transistor, this transistor is prevented from operating in its linear region, which would otherwise cause a decrease in the bandwidth of the amplifier.…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.