Digital Electronics - Engineering

Q1:

For a MOD-12 counter, the FF has a tpd = 60 ns The NAND gate has a tpd of 25 n sec. The clock frequency is

A 3.774 MHz

B > 3.774 MHz

C < 3.774 MHz

D 4.167 MHz

ANS:A - 3.774 MHz

For a proper working, the clock period should be equal to or greater than tpd = Mod 12 - 4FFs = 4 x 60 = 240 nsec. Total tpd = 240 + 25 = 265 nsec. = fc and fc = 3.774 MHz.