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. 17, 1994
Filed:
May. 26, 1993
Ali E Zadeh, Sierra Madre, CA (US);
Siemens Pacesetter, Inc., Sylmar, CA (US);
Abstract
A sense amplifier adapted for use with a cardiac pacer or the like includes a constant gain filter, a window comparator circuit and a programmable threshold reference generator circuit. The reference generator circuit generates a programmable window (reference) voltage used by the window comparator circuit to determine whether an input signal, amplified by the constant gain filter, exceeds the window voltage. The reference generator circuit is based on a bipolar junction device having an adjustable emitter area through which a constant current flows. The emitter area is adjusted in response to a control signal. As the emitter area changes as controlled by the control signal, the voltage across the device changes. In a preferred embodiment, a parallel combination or network of switched bipolar junction devices is used to realize the adjustable emitter area. The bipolar junction devices are switched into and out of operation in response to the control signal, thereby increasing or decreasing the net emitter area of the network. When the constant current flows through the network, a precisely controlled adjustable reference voltage is thus generated as a function of the net emitter area.