DDR PHY power collapse circuit for multimode double data rate synchronous dynamic random access memory

A transmitter circuit comprising:

• a first driver circuit configured to drive an input/output pad in an integrated circuit device, the first driver circuit comprising a thin-oxide transistor configured to couple the input/output pad to a first voltage rail when the transmitter circuit is operated in a first mode;
• a second driver circuit configured to couple the input/output pad to the first voltage rail when the transmitter circuit is operated in a second mode;
• a gate pullup transistor configured to couple a gate of the thin-oxide transistor to a second voltage rail when voltage of a third voltage rail is collapsed to a zero-volt level;
• and
• a switch configured to block transmission of a gating signal to the gate of the thin-oxide transistor when the voltage of the third voltage rail is collapsed to the zero-volt level,
• wherein the first voltage rail and the second voltage rail have a same voltage level when the transmitter circuit is operated in the first mode, and wherein the first voltage rail and the second voltage rail have different voltage levels when the transmitter circuit is operated in the second mode.

An apparatus, comprising:

• means for driving an input/output pad provided in an integrated circuit device, including a thin-oxide transistor in a first driver circuit that is active when the apparatus is operated in a first mode and that is configured to couple the input/output pad to a first voltage rail when active;
• means for pulling a gate of the thin-oxide transistor to a second voltage rail when the apparatus is operated in a second mode, the second voltage rail supplying power at a voltage level of greater magnitude than the voltage at which the first voltage rail supplies power;
• and
• means for blocking transmission of a gating signal to the gate of the thin-oxide transistor when the apparatus is operated in the second mode, wherein the gating signal is provided by a circuit powered by a third voltage rail, the first voltage rail supplying power at a voltage level of greater magnitude than the voltage at which the third voltage rail supplies power.

An apparatus, comprising:

• means for driving an input/output pad provided in an integrated circuit device, including a thin-oxide transistor in a first driver circuit that is active when the apparatus is operated in a first mode and that is configured to couple the input/output pad to a first voltage rail when active, and further including a second driver circuit that is active when the apparatus is operated in a second mode and that is configured to couple the input/output pad to the first voltage rail when active;
• means for pulling a gate of the thin-oxide transistor to a second voltage rail when voltage of a third voltage rail is collapsed to a zero-volt level;
• and
• means for blocking transmission of a gating signal to the gate of the thin-oxide transistor when the voltage of the third voltage rail is collapsed to the zero-volt level,
• wherein the first voltage rail and the second voltage rail have a same voltage level when the apparatus is operated in the first mode, and wherein the first voltage rail and the second voltage rail have different voltage levels when the apparatus is operated in the second mode.

A method for operating a transmitter circuit, comprising:

• configuring a first driver circuit to drive an input/output pad in an integrated circuit device when the transmitter circuit is operated in a first mode, the first driver circuit comprising a thin-oxide transistor configured to couple the input/output pad to a first voltage rail when the transmitter circuit is operated in a first mode;
• configuring a thick-oxide gate pullup transistor to couple a gate of the thin-oxide transistor to a second voltage rail when the transmitter circuit is operated in a second mode, the second voltage rail supplying power at a voltage level of greater magnitude than the voltage at which the first voltage rail supplies power;
• turning on a switch when the transmitter circuit is operated in the first mode, wherein a gating signal is provided to the gate of the thin-oxide transistor when the switch is turned on;
• and
• turning off the switch when the transmitter circuit is operated in the second mode, wherein the gating signal is blocked from the gate of the thin-oxide transistor when the switch is turned off,
• wherein the gating signal is provided by a circuit powered by a third voltage rail, the first voltage rail supplying power at a voltage level of greater magnitude than the voltage at which the third voltage rail supplies power.

A method for operating a transmitter circuit, comprising:

• configuring a first driver circuit to drive an input/output pad in an integrated circuit device when the transmitter circuit is operated in a first mode, the first driver circuit comprising a thin-oxide transistor configured to couple the input/output pad to a first voltage rail when the transmitter circuit is operated in a first mode;
• configuring a second driver circuit to couple the input/output pad to the first voltage rail when the transmitter circuit is operated in a second mode;
• configuring a gate pullup transistor to couple a gate of the thin-oxide transistor to a second voltage rail when voltage of a third voltage rail is collapsed to a zero-volt level;
• and
• configuring a switch to block transmission of a gating signal to the gate of the thin-oxide transistor when the voltage of the third voltage rail is collapsed to the zero-volt level,
• wherein the first voltage rail and the second voltage rail have a same voltage level when the transmitter circuit is operated in the first mode, and wherein the first voltage rail and the second voltage rail have different voltage levels when the transmitter circuit is operated in the second mode.