A Robust 90-nW Power-On Reset Circuit with Brown-Out Detection for RF Energy-Harvesting

This paper presents an ultra-low-power power-on
reset (POR) circuit with integrated brown-out detection (BOD) for
enhanced robustness in RF energy-harvesting power management
systems. Implemented in a 180-nm 1P6M CMOS technology,
the proposed POR circuit is part of a comprehensive power
management system that also incorporates a power harvester, a dc
limiter, and a low-dropout regulator (LDO) with voltage reference.
The POR ensures safe startup, while the BOD ensures reliable
operation after short supply voltage glitches occur. Operating from
a supply voltage of 1 V, the circuit consumes only 90 nW static
power and occupies 0.003 mm2 of silicon area. It achieves stable
trip voltages of VT,POR=0.73 V and VT,BOR=0.64 V with small
variations of ±22.9 mV and ±24.3 mV, respectively, within a
1σ confidence interval. Brown-out events as short as 3.4 μs are
reliably detected. The combination of ultra-low power, compact
area, and robust BOD threshold stability makes the proposed
POR circuit ideally suited for fully autonomous wireless RF-
powered mixed-signal system-on-chip (SoC) and other low-power
energy-harvesting applications that demand reliable startup and
continuous operation under variable power conditions.