Patent ID: 7403052
Filing Date: 2008-07-22
Classification: G01R,G11C,H03K

Abstract:
1. An apparatus that is arranged to cooperate with a thermal-voltage generator circuit to assert a power-on reset (POR) signal during a start-up transient condition, wherein the thermal-voltage generator circuit includes a first bipolar junction device, a second bipolar junction device, and a resistor, the apparatus comprising: an imbalanced comparator circuit comprising a first MOS transistor, a second MOS transistor and a current source are arranged to cooperatively operate as a differential pair with an intentional input referred offset, wherein a gate of the first MOS transistor is coupled to a first internal point of the thermal-voltage generator circuit, a gate of the second MOS transistor is coupled to a second internal point of the thermal-voltage generator circuit, and a drain of the second MOS transistor is arranged as an output of the imbalanced comparator circuit; and an inverter circuit that is arranged to generate the POR signal responsive to the output of the imbalanced comparator circuit, wherein the cooperative operation of the imbalanced comparator circuit and the inverter circuit are arranged to evaluate the start-up transient condition such that the POR signal is asserted during the start-up transient condition until the thermal-voltage generator circuit is detected as reaching a target operating condition for stable operation.