Hii
I need to design a circuit in which 0 to 12V square wave (32KHz) should be converted 0 to 3V3 or 0 to 5V square wave(32KHz) which is given as input of the IO pin of Microcontroller or FPGA . Can anyone suggest me circuit for this ...

I have a thought of using voltage divider... This can be used for DC voltages
are the below circuits can be used

 

There are lots of designs for level shifters. Here's one that XBee uses:



What's wrong with the first (mosfet) circuit you show, aside from inverting the signal? You might want to add a pull-down resistor on the gate to be sure it turns off (depends on source impedance).

 

If you can rely on the max voltage, a simple two resistor divider should be fine. Use about 10K for the lower resistor and the builtin diodes on the input will give adequate protection.

Bob

 

Ditto. Why complicate it? The input impedance load of your IO should be very high, so two resistors is all you need.