A 50V, 1.45ns, 4.1pJ High-Speed Low-Power Level Shifter for High-Voltage DCDC Converters

Abstract

The level shifter and the floating gate supply for high-side transistors are a major challenge in high-voltage DCDC converters. This paper presents a high-speed and power-efficient level shifter for voltages of up to 50 V, suitable for both PMOS and NMOS power FETs. A switching node falling edge detection allows both, a sensitive and safe signal detection. This enables a robust operation during steep dv / dt transitions and a power consumption as low as 4.1 pJ per switching cycle, which is a reduction of more than 40 % compared to prior art. An active clamping circuit prevents common mode displacement currents into the high-side supply. The level shifter is implemented in a 180 nm BiCMOS technology. Measurements confirm a 50 V 120 MHz high-speed operation of the level shifter with a rising / falling propagation delay of 1.45 ns /1.3 ns, respectively. The dv / dt robustness has been confirmed by measurements for transitions up to 6 V / ns.