A 0.45V-to-2.7V inductive-coupling level shifter

This paper presents a 0.45V-to-2.7V level shifter utilizing inductive coupling. Since primary and secondary coils are AC-coupled, each coil can be biased at arbitrary voltage independent from the conversion level difference. This enables both the primary and the secondary circuits to operate at the optimal operating region. In addition, the inductive coupling itself can provide an additional intermediate level-shifting by exploiting a coil-turn ratio between the primary and the secondary coils. As a result, wide-range voltage level conversion can be achieved. Test chip measurement in 65nm CMOS demonstrates voltage level conversion from 0.45V to 2.7V. Compared to a conventional level shifter, the primary voltage is reduced by 0.24V. In addition, the energy-delay product is reduced to 1/8.