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.

Date of Patent:
Aug. 28, 1990

Filed:

Jan. 23, 1989
Applicant:
Inventors:

Barry W Herold, Boca Raton, FL (US);

Omid Tahernia, Coconut Creek, FL (US);

Assignee:

Motorola, Inc., Schaumburg, IL (US);

Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
H03K / ;
U.S. Cl.
CPC ...
377 48 ; 377108 ; 377117 ; 377121 ; 377122 ;
Abstract

A high speed CMOS divide by 4/5 prescaler circuit comprises first, second, third, fourth, and fifth inverter stages. When a modulas control signal is low, the prescaler operates as five clocked inverters in series having an output which is fed back to the input of the initial stage. That is, the circuit operates as a five stage clocked ring oscillator wherein only one output changes on each clock edge. When a modulas control signal is high indicating that a divide by four is desired, the counter operates as a five stage ring oscillator for seven clock edges. On the eighth edge, feed forward circuitry forces the last three stages to change states simultaneously.


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