Appeal No. 1999-0153
Application No. 08/488,394
either a synchronous clock signal or an asynchronous clock
signal. The test circuitry includes two multiplexers for
selecting between test signal clocks and normal function
clocks. For the portion of the circuit to be tested that uses
internal or synchronous signals, the first multiplexer selects
between the normal internal functional clock and a test clock.
For the portion of the tested circuit that utilizes external
or asynchronous clock signals, the second multiplexer selects
between the external clock and the output of the first
multiplexer. Appellants assert at page 81 of the
specification that the described arrangement allows the
internal clock signal or a test clock signal to be supplied to
all portions of a circuit to be tested regardless of whether
the circuit is normally clocked by synchronous or asynchronous
signals.
Claim 1 is illustrative of the invention and reads as
follows:
1. A test circuit for controlling the testing of a
circuit having portions using either synchronous or
asynchronous clock signals, comprising:
a first multiplexer for selectively providing as an
output either said synchronous clock signal or a test clock
2
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