The power management unit is an essential assembly in precision applications where reference voltages with increased accuracy are required. The design of these circuits is a challenge, especially when it comes to the automotive field, where supply voltages can vary significantly (between 3.3 and 40 V).

The power management unit consists of a voltage reference, a voltage stabilizer, a bias circuit, a monitoring block and a pre-stabilizer with buffer.

The article presents the design, optimization and implementation of the bandgap voltage reference circuit that must provide a stable and accurate reference voltage, independent of process variations with temperature and supply voltage.

To reduce process variations, bipolar transistors were used because they have low variations with the manufacturing process. The base-emitter voltage of these transistors is approximately 0.6V at room temperature (27°C) independent of transistor dimensions or doping. In contrast, the threshold voltage of a MOS transistor is influenced by the thickness of the oxide layer, its quality, as well as the concentration of impurities present in both the transistor channel and the pol-ysilicon gate. For the implementation of the circuit at the schematic and layout level, the Virtuoso Schematic Editor and Virtuoso Layout Suite programs provid-ed by Cadence were used.