Friday, December 17, 2010

Sizing a n-input standard gate (where n≠1)

Load Capacitance = CLOAD

Input Capacitance of the n-input NAND gate = CN

Beta ratio of n-input NAND gate = βN

Input Capacitance of equivalent inverter = CINV

Beta ratio of equivalent Inverter = βINV

(a) Logical Effort:

(b) Assume an inverter in place of the n-input NAND gate:

Now, the equivalent pull-down strength of the n-input NAND gate is:

Hence, adding WNN and WPN we get CN:


E.g. for ND2, βN = 1 and for INV βINV = 2:

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