Active quadrature current reference source

US4296369A · kind A · utility

Assignee

• Canadian Patents & Dev. Limited · CA

Inventors

• William J. Moore · Lilburn, US
• Norbert L. Kusters · Ottawa, CA
• Eddy So · Ottawa, CA

Key dates

• Filing date: Apr 7, 1980
• Grant date: Oct 20, 1981
• Expiry date: Apr 7, 2000

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R35/007
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

This reference source provides a current which is of relatively high magnitude and which leads the voltage by substantially 90.degree.. It includes a reference capacitor which is highly stable and pure but of low capacitance, and a power capacitor which has a high capacitance. The capacitors are connected together at one end for coupling to a voltage source. A current comparator compares the currents flowing through the reference capacitor and the power capacitor, and provides a difference signal. A circuit generates a current in response to the difference signal and adds the generated current to the current through the power capacitor resulting in a current having a waveform and phase substantially identical to the reference capacitor current which leads the voltage source voltage by substantially 90.degree..