17.11 A 0.65ns-response-time 3.01ps FOM fully-integrated low-dropout regulator with full-spectrum power-supply-rejection for wideband communication systems

High performance low-dropout regulators (LDOs) are indispensable in a systemon-a-chip (SoC) due to their low output noise, fast transient response and good power supply rejection (PSR) characteristics. In general, differential analog circuit loads need an LDO with high PSR, digital circuit loads need an LDO with fast load transient response, while single-ended analog/RF circuit loads need an LDO with both high PSR and fast transient response. Figure 17.11.1 shows an LDO embedded in an optical receiver that helps improve the sensitivity of the front-end system. On-chip LDOs with PSR in the GHz range are in high demand for wideband optical communication systems because there is only one photo detector in the optical receiver and supply voltage variations would degrade its sensitivity severely.