Direct current sum bandgap voltage comparator

Abstract

A direct current sum bandgap voltage comparator for detecting voltage changes in a power supply. The direct current sum bandgap voltage comparator includes a summing node, current sources connected to the summing node and the power supply, and an indicator circuit connected to the summing node. Each current source supplies a current to the summing node wherein the summing node voltage level is responsive to the currents supplied. The indicator circuit is responsive to changes in the summing node voltage level and generates at an output a logical signal at one state when the summing node voltage level is greater than a predetermined value and generates the logical signal at the output at another state when the summing node voltage level is less than the predetermined value, the predetermined value corresponding to a preselected power supply voltage.

Description

[0001]This is a Continuation of application Ser. No. 08 / 606,233, filed Feb. 23, 1996, now abandoned, which is a Continuation of application Ser. No. 08 / 056,301, filed Apr. 30, 1993, now abandoned.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to integrated circuits and in particular to MOS integrated circuits. Still more particularly, the present invention relates to bandgap reference circuits in insulated gate FET semiconductor integrated circuits.[0004]2. Description of the Prior Art[0005]In some situations it is desirable to provide retention of data in integrated circuits such as memory devices. A number of circuits are commercially available for retaining data in SRAMS when power is removed. These devices are often known as “zero power circuits”. Typically, in a zero power circuit, the contents of the circuit are protected in the event that the power supply voltage to that circuit drops below some predetermined or preselected thres...

AI Technical Summary

Problems solved by technology

One drawback with a typical bandgap reference circuit is that a large number of devices are needed for implementation.

As a result, a large amount of area on a semiconductor chip is required.

In addition to the area problem, typical bandgap reference circuits also are fairly sensitive to noise within the circuit.

For example, active memory circuits are usually noisy and known bandgap circuits used with active memories circuits are usually sensitive to the noise generated.

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