Computer Laboratory

Technical reports

High precision timing using self-timed circuits

Scott Fairbanks

January 2009, 99 pages

This technical report is based on a dissertation submitted September 2004 by the author for the degree of Doctor of Philosophy to the University of Cambridge, Gonville and Caius College.

The PDF file provided by the author has minor font problems.

Abstract

Constraining the events that demarcate periods on a VLSI chip to precise instances of time is the task undertaken in this thesis. High speed sampling and clock distribution are two example applications. Foundational to my approach is the use of self-timed data control circuits.

Specially designed self-timed control circuits deliver high frequency timing signals with precise phase relationships. The frequency and the phase relationships are controlled by varying the number of self-timed control stages and the number of tokens they control.

The self-timed control circuits are constructed with simple digital logic gates. The digital logic gates respond to a range of analog values with a continuum of precise and controlled delays. The control circuits implement their functionality efficiently. This allows the gates to drive long wires and distribute the timing signals over a large area. Also gate delays are short and few, allowing for high frequencies.

The self-timed control circuits implement the functionality of a FIFO that is then closed into a ring. Timing tokens ripple through the rings. The FIFO stages use digital handshaking protocols to pass the timing tokens between the stages. The FIFO control stage detects the phase between the handshake signals on its inputs and produces a signal that is sent back to the producers with a delay that is a function of the phase relationship of the input signals.

The methods described are not bound to the same process and systematic skew limitations of existing methods. For a certain power budget, timing signals are generated and distributed with significantly less power with the approaches to be presented than with conventional methods.

Full text

PDF (13.2 MB)

BibTeX record

@TechReport{UCAM-CL-TR-738,
  author =	 {Fairbanks, Scott},
  title = 	 {{High precision timing using self-timed circuits}},
  year = 	 2009,
  month = 	 jan,
  url = 	 {http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-738.pdf},
  institution =  {University of Cambridge, Computer Laboratory},
  number = 	 {UCAM-CL-TR-738}
}