A 2A Fully Analog Distribution LDO with Noise Immunity for an SoC

초록

As system-on-chip (SoC) technologies advance, devices have suffered from significant thermal dissipation. Because long-term exposure to high temperature degrades SoC performance, it is necessary to manage the temperature in the devices. Consequently, low-dropout regulators (LDO) that supply the load current (ILOAD) by distributing the ILOAD through multiple power transistors have been introduced [1-5]. In these distribution LDOs (DISLDOs), it is critical to balance the currents supplied by each power transistor (MP) for effective thermal distribution. There are two approaches to implementing the DISLDO: 1) digital DISLDOs; and 2) analog DISLDOs. In the SoC, the noise becomes severe as the SoC advances. Since the MPs of the DISLDO need to be located far from each other and transfer signals to each other, digital DISLDOs are highly suitable for SoCs because digital DISLDOs deliver digital signals to each other, which are more insensitive to noise than analog signals [1-5], as shown in Fig. 21.6.1 (top). However, digital LDOs usually consume a larger static current, which results in a lower current efficiency, and a larger output voltage ripple. Furthermore, in digital DISLDOs, ILOAD might not be evenly distributed if the parasitic resistances of the power lane are different. This is because the MPs in digital DISLDOs are considered as resistors since the MPs operate in the triode region, and the output voltage is determined by the voltage division. On the other hand, analog DISLDOs can evenly distribute ILOAD regardless of the parasitic resistances of the power lane because the MPs in the analog LDO normally operate in the saturation region, which considers the transistors as current sources. However, as mentioned previously, the noise from the SoC interferes with the analog signals transferred between MPs. Therefore, the output of analog DISLDOs becomes considerably noisy. For this reason, analog DISLDOs have not been practical for use in SoCs. © 2025 IEEE.