Patent ID: 6316978
Filing Date: 2001-11-13
Classification: H03K

Abstract:
A comparator circuit having a first state and a second state, a threshold potential for transition from the first state to the second state, a second threshold potential for transition from the second state to the first state, and hysteresis characteristics that are independent of process, temperature, and supply voltage variations, wherein the comparator circuit asserts a binary output signal, whose value is one of a first value and a second value, in response to an input potential and a reference potential, said comparator circuit comprising:a comparator having an output and two comparator inputs, wherein the comparator asserts the binary output signal at the output; andadditional circuitry coupled to the comparator inputs and coupled to receive the input potential, and including resistors and a current source, wherein the current source includes a first subset of the resistors, a second subset of the resistors is not included in the current source, the current source is coupled to the output and configured to draw a first current when the output signal has the first value and to draw a second current when the output signal has the second value, and the current source is configured such that each of the first current and the second current is independent of all parameters other than the reference potential and a resistance of each resistor of the first subset of the resistors, so that each of the threshold potential and the second threshold potential depends only on the reference potential and on ratios of resistances of pairs of the resistors.