Give me a example of level shifter circuit

[fxxjssc]

hi all,
My chip operate with vdd=1.8v but i want to accept 3.3v and 5v signal
from out of chip. So my IO would like shifter 3.3v and 5v level to 1.8v which
my chip could handle.
My process is 0.18u with 1.8v power. Further more, this process has
3.3v and 5v nmos/pmos special for I/O pad.
please give me some advice! thanks in advance!!
wishes
fxxjssc

 

[suhas_shiv]

You could refer to some I/O design papers to get an idea of level shifters. Maybe refering to some LVDS design papers might help.

"Low-power LVDS Receiver for 1.3Gbps Physical Layer(PHY) Interface"

by Gunjan Mandal and Pradip Mandal.

The above paper will give you some insight.

 

[DenisMark]

The simple level shifter can be maked on the basis of differential logic. Look for patents on uspto.gov (free site, search for "levelshift"), there are many examples.