Patent ID: 7463074
Filing Date: 2008-12-09
Classification: G01R,H03K

Abstract:
1. An integrated circuit, comprising: an input for receiving a supply voltage; a voltage source connected to the input to receive the supply voltage and configured for generating a reference voltage on the basis of the supply voltage, wherein the reference voltage is substantially independent of the supply voltage when the supply voltage is above a threshold level; a first device comprising a switch which switches when a switch voltage dependent on the supply voltage exceeds a minimum voltage; the first device being configured for determining whether the switch has switched; a second device for detecting the reference voltage generated by the voltage source; a third device, connected to receive outputs from the first device and the second device, for generating a ready signal indicating that the supply voltage is sufficient for performing functions of the integrated circuit, wherein the ready signal is generated when the first device indicates that the switch has switched and, concurrently, when the second device indicates that the reference voltage lies within a predetermined interval; and a plurality of different field-effect transistors, each comprising a gate, each gate being connected to the input such that a respective gate voltage is a function of the supply voltage, wherein for each of the plurality of different field effect transistors a respective first device is provided, and each device is configured to determine for the respective field-effect transistor whether its respective gate voltage exceeds its respective turn-on voltage, and wherein the third device is configured to generate the ready signal only when each respective gate voltage at each field-effect transistor exceeds its respective turn-on voltage.