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:
Oct. 25, 1988
Filed:
May. 12, 1987
Don W Zobel, Tempe, AZ (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
An integrated circuit sensor circuit (10) is disclosed which is operable in differential or single-ended modes at DC input potentials which can be below the integrated circuit substrate bias potential (ground). Substrate injection is prevented and the circuit is operable for input signals which can vary relatively widely with respect to the substrate bias potential. This is accomplished even though only a single polarity power supply (+5 volts) with respect to substrate bias potential is used for the integrated circuit. An input stage of an integrated circuit (16) comprises a pair of identical polarity transistors (23, 24) operated in a differential common base mode with an opposite polarity transistor (25) used to supply appropriate bias potential to the common base connection. This prevents substrate injection while maintaining a wide operative range for the sensor circuit. Additional substrate injection preventing circuitry (31) is provided to maintain the collectors of the differential input transistors above the integrated circuit substrate base potential, and input protection circuitry (32-35) is used to limit the magnitude of applied input signals.