Low voltage current mirror and CTAT current source and method
US5982201A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 13, 1998 |
| Grant date | Nov 9, 1999 |
| Priority date | — |
| Expiry date | Jan 13, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05F3/245
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A low voltage CTAT current source includes a bipolar transistor connected across two series-connected resistors. A voltage developed across the resistors turns on the transistor, making the current through the resistors CTAT. A second transistor supplies the resistor current; its base (if bipolar) is connected to the node between the resistors, which are selected to limit the transistor's base-collector forward bias and collector-emitter voltage to a preselected fraction of the first transistor's V.sub.be, allowing the CTAT current source to operate with supply voltages of less than two junction voltage drops. A PTAT current can be combined with the CTAT current to create a temperature-compensated current. A low voltage current mirror has the respective bases of a pair of cascoded transistors connected across a resistor which is also connected between the bottom transistor's collector and a programming current. When the transistors are matched, the top transistor's collector-emitter voltage about equals the voltage across the resistor, which is selected to establish a V.sub.ce just high enough to avoid saturation and allow the circuit to operate with only two unsaturating V.sub.ce …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.