Method and apparatus for process independent clock signal distribution
AssigneeInternational Business Machines Corporation
InventorRobert Paul Masleid
Life of this patent
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Abstract
A method and apparatus for restoring tracking in a circuit in which gate and metal capacitance vary independently. The present invention allows Shoji balancing to be extended to the situation where the gate and metal capacitance in a circuit vary independently across a process window. This is accomplished by regarding the inverting stage in a clock distribution system as a buildup mirror and applying the tracking principles of proportional composition. Loads are reflected through this mirror and resized by the buildup factor to extend Shoji balancing from just one process parameter setting to the entire process window.
Claims6
A clock distribution circuit comprising:
- (a) a driving stage;
- (b) an inverting stage driven by the driving stage;
- and
- (c) a load stage driven by the inverting stage, wherein the inverting stage has a ratio of transistor sizes equal to a ratio of transistor sizes of the load stage, wherein the load stage includes a load wire capacitance and a load gate capacitance, wherein the inverting stage comprises an inverting stage wire capacitance and an inverting stage gate capacitance, and wherein a ratio of the load wire capacitance to the load gate capacitance is equivalent to a ratio of the inverting stage wire capacitance to the inverting stage gate capacitance.
Dependencies are inferred from the claim text.