Patent Number: 8,797,082

Title: Apparatus and methods for clock characterization

Abstract: A system and method for efficiently performing timing characterization of high-speed clocks signals with low-speed input/output pins. An integrated circuit includes a clock generator that generates a high-speed clock signal. A clock characterizer circuit receives the high-speed clock signal. The clock characterizer generates a corresponding low-speed clock signal. The generated low-speed clock signal is output through a low-speed general-purpose input/output (GPIO) pin for measurement. The generated low-speed clock signal is sent to a sequential element for staging. The staging of the generated low-speed clock signal is done with sequential elements that use a reverse polarity of a clock signal than the polarity used by a previous stage. The high-speed clock signal is used for the staging. The output of each stage is sent to a low-speed GPIO pin for measurement.

Inventors: Ramaswami; Ravi K. (Cupertino, CA), Joordens; Geertjan (Sunnyvale, CA)

Assignee: Apple Inc.

International Classification: H03K 3/00 (20060101)

Expiration Date: 8/05/12018