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:
Mar. 27, 1990
Filed:
Aug. 25, 1987
Bernard L Morris, Allentown, PA (US);
American Telephone and Telegraph Company, AT&T Bell Laboratories, Murray Hill, NJ (US);
Abstract
A circuit is disclosed which converts CMOS logic input signals to ECL output signals. A pair of FETs, arranged as a conventional CMOS inverter, responds to the CMOS logic input signals and drives a bipolar transistor operating as a voltage follower. The emitter of the bipolar transistor serves as the output of the buffer providing the ECL output signals. A resistor having a predetermined resistance couples between a voltage source and the base of the bipolar transistor. First one of the pair of FETs couples a constant current source to the resistor and the base of the bipolar transistor when the buffer is supplying an ECL logical 'zero' logic signal. The current from the current source passing through the resistor establishes the ECL logical 'zero' output voltage. Second one of the pair of FETs shunts the resistor when the buffer is supplying an ECL logical 'one' output, allowing faster transitioning of the output of the buffer from an ECL logical 'zero' to a logical 'one'. Further, the current from the current source compensates for variations in the resistance of the resistor to assure a substantially constant difference between the ECL logical 'one' and the ECL logical 'zero' output voltages with variations in the resistance of the resistor from the manufacture thereof.