Integrated circuit having a precharging circuit

A memory comprising:

• a phase change element;
• a bit line coupled to one side of the element;
• a transistor having a source-drain path, one side of the source-drain path coupled to another side of the element;
• a word line coupled to a gate of the transistor;
• and
• a circuit to program the element to a selected one of three or more states, the circuit configured
• to precharge the bit line to a first bit line precharge voltage having a first bit line precharge amplitude and then to apply a voltage pulse having a first word line voltage amplitude to the word line if the element is to be programmed to a first selected state, and
• to precharge the bit line to a second bit line precharge voltage having a second bit line precharge voltage amplitude and then to apply a voltage pulse having a second word line voltage amplitude to the word line if the element is to be programmed to a second selected state,
• wherein the first bit line precharge voltage amplitude is smaller than the second bit line precharge voltage amplitude.

A memory comprising:

• a phase change element;
• a bit line coupled to one side of the element;
• an access device coupled to another side of the element;
• a word line coupled to the access device for controlling the access device;
• and
• means for programming the element to a selected one of three or more states, the means including:
• means for precharging the bit line to a first bit line precharge voltage having a first bit line precharge voltage amplitude and then for applying a voltage pulse having a first word line voltage amplitude to the word line if the element is to be programmed to a first selected state, and
• means for precharging the bit line to a second bit line precharge voltage having a second bit line precharge voltage amplitude and then for applying a voltage pulse having a second word line voltage amplitude to the word line if the element is to be programmed to a second selected state,
• wherein the first bit line precharge voltage amplitude is smaller than the second bit line precharge voltage amplitude.

A method for programming a memory cell to a selected one of three or more states, the method comprising:

• precharging a bit line coupled to one side of the phase change element to a first bit line precharge voltage having a first bit line precharge voltage amplitude and then applying a voltage pulse having a first word line voltage amplitude to a word line coupled to an access device for controlling the access device if the element is to be programmed to a first selected state;
• and
• precharging the bit line to a second bit line precharge voltage having a second bit line precharge voltage amplitude and then applying a voltage pulse having a second word line voltage amplitude to the word line if the element is to be programmed to a second selected state,
• where in the first bit line precharge voltage amplitude is smaller than the second bit line precharge voltage amplitude.

A method for programming a phase change element to a selected one of three or more states, the method comprising:

• applying a first bit line precharge voltage having a first bit line precharge amplitude to a bit line coupled to the phase change element;
• setting the phase change element to an initial state by applying a first voltage pulse having a first word line voltage amplitude to a word line of a transistor coupled to the element;
• setting the phase change element to the selected state by applying a second voltage pulse having a second word line voltage amplitude if the element is to be programmed to a first selected state;
• and
• setting the phase change element to the selected state by applying a second voltage pulse having a third word line voltage amplitude if the element is to be programmed to a second selected state,
• wherein the first, second, and third word line voltage amplitudes are different.

A memory comprising:

• a phase change element having a first side and a second side;
• one of a common and a ground coupled to the first side of the element;
• an access device coupled to the second side of the element and a bit line;
• a word line coupled to the access device for controlling the access device;
• and
• a circuit to program the element to a selected one of three or more states, the circuit configured
• to precharge the bit line to a first bit line precharge voltage having a first bit line precharge amplitude and then to apply a voltage pulse having a first word line voltage amplitude to the word line if the element is to be programmed to a first selected state, and
• to precharge the bit line to a second bit line precharge voltage having a second bit line precharge voltage amplitude and then to apply a voltage pulse having a second word line voltage amplitude to the word line if the element is to be programmed to a second selected state,
• wherein the first bit line precharge voltage amplitude is smaller than the second bit line precharge voltage amplitude.