Current mode analog-to-digital converter

A system of measuring current, comprising:

• an analog to digital converter having a current input node, a current output node, and a digital output node;
• a reference current source for outputting a plurality of different reference currents to said analog to digital converter,
• wherein said analog to digital converter comprises a differential current comparator that is configured to compare an input current received at said current input node with said plurality of different reference currents to produce a digital representation of said input current,
• wherein said differential current comparator comprises a separate current comparator circuit for comparing each said reference current to said electrical current from said current input node, each said current comparator circuit comprising a pair of cross-coupled metal oxide semiconductor (MOS) inverters such that a source of an nMOS transistor in each said inverter is electrically coupled to a respective current mirror, a first of said current mirrors being configured to mirror said electrical current from said current input node and a second of said current mirrors being configured to mirror said reference current corresponding to said comparator circuit, and
• wherein said analog to digital converter is further configured to output said digital representation of said input current at said digital output node.

A method of obtaining a digital representation of an analog current signal, said method comprising:

• providing an analog to digital converter having a current input node;
• providing an electrical current representative of a parameter of interest at said current input node of said converter;
• deriving a digital representation of a measurement of said electrical current in said analog to digital converter by comparing said electrical current to one or more reference currents using a differential current comparator;
• and
• providing said digital representation at an output node of said converter;
• wherein said differential current comparator comprises a separate current comparator circuit for comparing each said reference current to said electrical current from said current input node each said current comparator circuit comprising a pair of cross-coupled metal oxide semiconductor (MOS) inverters such that a source of an nMOS transistor in each said inverter is electrically coupled to a respective current mirror, a first of said current mirrors being configured to mirror said electrical current from said current input node and a second of said current mirrors being configured to mirror said reference current for said comparator circuit.