| 摘要 |
A testing system is provided with a pseudo random number generating circuit which generates a pseudo random number on the basis of a 125 MHz clock output from a 5-multiply circuit inside a clock recovery circuit, and an expected value generating/comparator circuit which collates a 125 Mbps recovered data output from the clock recovery circuit with an expected value data each 5 bits, and outputs the collation result as a 1-bit test output. The clock recovery circuit and the testing system are provided on the same LSI and are operated at a 125 MHz high frequency clock. However, the clock recovery circuit outputs a test output as recognized as a 25 MHz low speed data in the outside of LSI to the external elements.
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