Power on reset circuit of 915MHz RFID tags

Power on reset circuit provides a reset signal for the entire system into normal working condition. When power reaches normal operating voltage and remains stable, power on reset circuit provides one rectangular pulse signal which has a steep edge for the digital baseband part of the tag. After reset, POR circuit is isolated with the follow-up circuits, having good stability. In this paper, we designed two new static ultra-low power consumption power-on reset circuits. The first circuit uses Schmitt triggers for signal threshold detection and a certain delay. The peak current of the first circuit is 31uA, with a static current being 33 pA. The second circuit is based on a clamp circuit and PMOS gate cross-coupled circuit which greatly reduces the static current (190 pA). And the peak current of the second circuit is 21 μA.