Bias circuit and differential amplifier having stabilized output swing
US5451898A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 12, 1993 |
| Grant date | Sep 19, 1995 |
| Priority date | — |
| Expiry date | Nov 12, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/145
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A differential circuit is provided that generates a differential output voltage .DELTA.V that does not vary when the power supply voltage changes and/or when the field effect transistor conductance changes. The bias circuit connected to the differential amplifier stabilizes the output voltage swing .DELTA.V to be insensitive to change in supply voltage and/or transconductance. A feedback loop is provided to drive the voltage to a predetermined voltage dependent upon the threshold voltage of the transistors used (e.g., the threshold voltage of a PMOS transistor). The voltage stabilizes the current source of the differential amplifier via a current mirror coupled to the feedback loop. Therefore, the resultant differential output voltage .DELTA.V is equal to the transistor threshold voltage. As the transistor threshold voltage is independent of the power supply voltage and device transconductance, the differential amplifier output .DELTA.V is stabilized against variations in power supply voltage and transconductance.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.