Appeal No. 2006-1204
Application No. 10/379,006
Invention
Appellants’ invention relates generally to a method, an
apparatus, and a computer-readable storage medium containing
instructions for calibrating the impedance of a driver circuit
(225) in an integrated circuit (IC) package (200), as depicted in
figure 2. The driver circuit (225) has a plurality of
impedances (300) and is coupled to an external load (210) through
a PAD (215), which provides a path (220) for signals to pass from
the driver circuit and the load. See also figure 3A. The IC
package (200) includes a synchronous circuit (260) that monitors
the phase difference between one or more internal clock signals
and an external clock signal. See also figure 4, item 400. Upon
detecting a phase difference between the clock signals, the
synchronous circuit (260) issues an update signal (270) to a
controller (230) indicative of a possible impedance mismatch
between the driver circuit (225) and the external load (210).
The controller (230) in turn sends a test signal (250) to a test
driver circuit (240) and a resistor (245) to determine whether an
impedance mismatch actually exists between the external load
(210) and the driver circuit (225). See also figure 4, item 410.
In response, the test driver circuit (240) provides a signal
2
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