Patents by Inventor J. Christopher Smallwood

J. Christopher Smallwood has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Lock detect circuit for detecting a lock condition in a phase locked loop and method therefor
    Patent number: 5394444
    Abstract: A lock detect circuit (18) determines when a reference frequency and a feedback frequency are frequency locked using a reference counter (32) and a feedback counter (36). The reference counter (32) and the feedback counter (36) are clocked by the reference frequency and the feedback frequency, respectively. After a first period of time, the outputs of the counters are compared. The outputs of the counters are also compared at the end of a second period of time. To be frequency locked, the two count values must be equal at both the end of the first and the second periods of time. A count window is generated from the reference frequency signal to indicate a range of frequencies for which the feedback frequency is locked. Once lock is achieved, the count window is widened such that the feedback frequency is still within a lock range when some aliasing occurs.
    Type: Grant
    Filed: July 12, 1993
    Date of Patent: February 28, 1995
    Assignee: Motorola, Inc.
    Inventors: John M. Silvey, J. Christopher Smallwood