Threshold voltage-independent MOS current reference

US6570436B1 · kind B1 · utility

Assignee

• DIALOG SEMICONDUCTOR INC. · DE

Inventors

• Frank Kronmueller · Neudenau, DE
• Horst Knoedgen · Munich, DE

Key dates

• Filing date: Nov 30, 2001
• Grant date: May 27, 2003
• Expiry date: Nov 30, 2021

Classification

• Technology area (CPC G): Physics
• CPC primary: G05F3/262
• WIPO field: Control
• WIPO sector: Instruments

Abstract

A new current reference circuit is achieved. This current reference circuit is based on MOS transistors but does not depend upon the threshold voltage. The circuit comprises, first, a first MOS transistor having gate, drain, and source. A gate voltage value is coupled from the gate to the source. A second MOS transistor has gate, drain, and source. The second MOS transistor is of the same size and type as the first MOS transistor. The source is coupled to said first MOS transistor source. The gate voltage value plus a delta voltage value is coupled from the gate to the source. A means is provided for forcing a drain voltage value from the drain to the source of the first MOS transistor and from the drain to the source of the second MOS transistor. The first MOS transistor and the second MOS transistor conduct drain currents in the linear mode. Finally, a means is provided for subtracting the first MOS transistor drain current from the second MOS transistor drain current to thereby create a current reference value. The current reference value does not depend upon the threshold voltage of the first and second MOS transistors. The circuit may be further applied to create a nearly zero…