The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 18, 1995
Filed:
Jun. 16, 1993
Frank L Thiel, Richardson, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A voltage reference circuit (2) is provided that operates with a minimal amount of headroom. A low threshold voltage transistor (M71) is incorporated into a bandgap reference circuit (Q4, Q3, Q2, Q1, R2 and R1) to eliminate base current errors that a current mirror (Q3 and Q4) of the bandgap may introduce. A low threshold voltage transistor (M72) is incorporated into the gain circuit (Q7) to eliminate base current error that a gain transistor (Q7) may introduce. A third low voltage transistor (M73) may be incorporated into a feedback circuit (QS) to eliminate any voltage variations possibly caused by the addition of the first two low threshold transistors (M71 and M72). Using P channel type MOS low voltage threshold transistors for base drive cancellation allows the circuit to operate effectively with a very low input voltage of around about 2.0 volts. These CMOS low threshold devices absorb process variations in the transistors that may occur between different lots of silicon and thereby provide a more manufacturable voltage reference circuit.