Precision tuning of a phase-change resistive element

A method of programming a network of on-chip phase-change resistors to a target resistance, said method comprising:

• providing an off-chip resistor with a known resistance;
• establishing a constant current between said off-chip resistor and said network of on-chip resistors network using a circuit;
• comparing an output voltage of said on-chip resistor in said circuit to a predetermined reference voltage;
• and
• programming at least one on-chip resistor in said on-chip resistor network until said output voltage is equal to said predetermined reference voltage,
• wherein said predetermined reference voltage is equal to a supply voltage reduced by a predicted voltage consumption of said circuit given said known resistance of said off-chip resistor and said target resistance of said on-chip resistor network.

A device for programming the resistance of an on-chip phase-change resistor to a target resistance, said device comprising:

• said on-chip resistor;
• an off-chip resistor, having a known resistance, electrically connected to said on-chip resistor;
• a state-machine electrically connected to said on-chip resistor;
• and
• a power source electrically connected to said on-chip resistor and said off-chip resistor and adapted to input a supply voltage to said on-chip resistor and said off-chip resistor,
• wherein a predetermined reference voltage is equal to said supply voltage reduced by a predicted amount of voltage consumption by said on-chip resistor and said off-chip resistor,
• wherein said predicted amount of voltage consumption is based upon said known resistance of said off-chip resistor and said target resistance of said on-chip resistor, and
• wherein said state-machine is adapted to analyze a difference between an output voltage from said on-chip resistor and said predetermined reference voltage to determine a resistance of said on-chip resistor compared to a known resistance of said off-chip resistor.

A device for programming the resistance of a network of on-chip phase-change resistors to a target resistance, said device comprising:

• said on-chip resistor network;
• an off-chip resistor, having a known resistance, electrically connected to said on-chip resistor network;
• a state-machine electrically connected to said on-chip resistor network;
• and
• a power source electrically connected to said on-chip resistor network and said off-chip resistor and adapted to input a supply voltage into said on-chip resistor network and said off-chip resistor,
• wherein a predetermined reference voltage is equal to said supply voltage reduced by a predicted amount of voltage consumption by said on-chip resistor network and said off-chip resistor;
• wherein said predicted amount of voltage consumption is based upon said known resistance of said off-chip resistor and said target resistance of said on-chip resistor network, and
• wherein said state-machine is adapted to analyze a difference between an output voltage from said on-chip resistor and said predetermined reference voltage to determine a resistance of said on-chip resistor network compared to a known resistance of said off-chip resistor.