Nested hysteretic current-mode single-inductor multiple-output (SIMO) boosting buck converter

Portable microsystems, which typically incorporate transceivers, analog/digital converters, microprocessors, and others, require several fast on-chip supplies to both function and save energy. Linear regulators are fast and compact, but also lossy, and although switched inductors are efficient, power inductors are bulky, which is why supplying several functions with one inductor is often an optimal compromise. Responding quickly to individual disruptions, however, is challenging when sharing one inductor with other loads, and bucking and boosting the battery voltage normally require more power switches. The 1.25-MHz single-inductor multiple-output (SIMO) converter presented here employs a buck stage to buck and boost 3.6 V to 0.8, 1.2, and 4.5 V and uses nested hysteretic current-mode control to respond within 1 μs to 20-mA load dumps across 0.8 and 1.2 V and 2 μs to 5-mA load dumps across 4.5 V. Simulations show that efficiency peaks at 91% 0/0 with a combined load of 45 mA.