| 摘要 |
A novel method for introducing delays in self timed memories is disclosed. In the proposed method, delays are introduced by introducing a capacitance on the path of signal to be delayed. The capacitances are realized by using idle lying metal layers in the circuit. The signal to be delayed is connected to these idle lying capacitances via programmable switches. The amount of delay introduced depends on the capacitance introduced in the path of signal which in turn depends on state of the switches. The state of the switches is controlled by delay codes provided externally to the delay introducing circuitry. Since, in the proposed method, idle-lying metal capacitances are utilized. the circuit can be implemented using minimum amount of additional hardware. Also delay provided by the proposed circuitry is a function of memory cell spice characteristics and core parasitic capacitances.
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