Mattingly, Stanger & Malur, P.C.
Device for regulating variation of delay time for data transfer between logic circuits
 The delay time for the transfer of data signals between pluralities of logic circuits is automatically regulated to be in a desired range. In order to regulate the delay time of the data signal transfer, a common standard signal SYNC is distributed to the logic circuits from a standard signal generator source. In the sending side of one logic circuit, the standard signal is applied through a selector circuit to a flip-flop circuit and then transferred to the receiving side of another logic circuit. Specifically, the transferred standard signal passes through a variable delay circuit to a flip flop circuit on the receiving side of the other logic circuit where it is compared with the standard signal received from the standard signal generator source, which has passed through a delay circuit of a standard delay value. The result of the comparison is used to adjust the variable delay circuit that controls the delay time for the transferred standard signal. Once the variable delay circuit is adjusted with the standard signal, the selector selects normal data signals for transfer between the logic circuits with the appropriate delay. The standard signal can also be used to synchronize the generation of test pattern signals generated in each of the logic circuits. 
Hitachi, Ltd.
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Tatsuya Hiroki Tetsuya
Saito Yamashita Umemura