but at a level too low to be read by the Pi. He solved this with a clever resistor ladder to shift the signals to straddle the 1.8 volt transition on the Pi, and after solving some noise problems ...

Will it be a step-up, a step-down, or do you need a bi-directional level shifter? If you decide not to use a dedicated part or a 5V tolerant gate in your design, here are a few of the many ...

For M11 and M12 the supply is connected to voltage level VDDL via M4 thus driving gate of M14 with logic level of VDDL. The supply for the cross coupled level shifter also connected to high voltage ...

All this leads to significant increases in power consumption and die size. The proposed circuit is a single supply level shifter to translate the signal from one power domain to another power domain.