How can we design a circuit using combinational circuit to double the frequency?

[haneet]

how can we design a ckt using combinational ckt to double the frequency?

 

[sree205]

plz help

there is this circuit which uses xor and inverters/buffers, which supposedly can double the frequency. but, as far as i know, i've not come across anyone using it.

this is how it works.

assign temp = !(!clk);
assign clk_twice = clk ^ temp;

idea is that, when this is synthesized, the '!' operator is synthesized as inverter with some propagation delay(Tpd). the Tpd is adjusted such that it's 1/4th the Tpd of XOR gate. so, when these two signals are xor'ed we get twice the frequency.

Added after 18 minutes:

This is only theoretical, if we try to synthesize using any tool, in all probabilities, it might remove the inverters.

 

[rameshsuthapalli]

plz help

Hi sree,

it willnot work in the real time u cant controll the tanshition time and theduty cycle is also a problem for that.

regards,
rameshs