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:
May. 15, 1990
Filed:
May. 01, 1989
John M Pigott, Phoeniz, AZ (US);
Robert B Jarrett, Tempe, AZ (US);
Motorola Inc., Schaumburg, IL (US);
Abstract
A negative voltage clamp circuit is coupled to an N-epi region within an IC for clamping the voltage applied thereto to a predetermined negative value without utilizing a negative power supply. A current supply provides a first current through a series combination diode and resistor such that a voltage is developed across the resistor. The base of a first transistor receives drive current from the current supply for providing a second current flowing through its collector-emitter conduction path. The first and second currents respectively flow through the collector-emitter conduction paths of second and third transistors which are configured as a cross-coupled pair. The base-emitter junction of the third transistor is responsive to an applied voltage for gating an appropriate magnitude of the second current to the output for limiting the applied voltage to a predetermined value approximately equal to the voltage developed across the resistor.