US 2006/0125529 A1 · Comparator for input voltages higher than supply voltage

Abstract

A comparator has first and second current paths, each passing from an input through a transistor, through a current source to ground, the second current path also having a reference voltage drop element coupled in series with the second input. The gates of the transistors are coupled to form a current mirror. The reference voltage drop element enables higher voltages to be input and compared to higher thresholds above an internal supply voltage level without the need for dividing resistors to reduce the input voltage. Avoiding such resistors means the power dissipation and the silicon area used can be kept lower. ESD vulnerability is reduced since the inputs are not coupled to gates of MOS transistors. Overvoltage protection across the source and gate of the second transistor can be added.

Claims12

Dependent claims

A comparator for comparing voltages of first and second inputs, comprising:

first and second current paths coupled to the first and second inputs respectively, the first current path passing from the first input through a first main electrode and a second main electrode of a first transistor, and through a first bias current source to a supply line;
the second current path passing through a reference voltage drop element, through a first main electrode and a second main electrode of a second transistor, and through a second bias current source to said supply line.

Dependencies are inferred from the claim text.

Comparator for input voltages higher than supply voltage

Life of this patent

Comparator for input voltages higher than supply voltage

Life of this patent

Abstract

Claims12