Method and apparatus for low-power charge transition in an I/O system of an integrated circuit
First Claim
1. Method for low-power charge transition in an integrated-circuit I/O system which comprises a plurality of capacitive loads which convert between a charged state at an operating voltage and a discharged state at ground during each of operation cycles of the I/O system, wherein the operation cycles are predetermined by an external clock signal, and of which plurality of said capacitive loads a first number of capacitive loads having the charged state converts from the charged state to the discharged state at ground, and a second number of capacitive loads having the discharged state converts from the discharged state to the charged state at the operating voltage, the method comprising the steps of:
- sharing the charge of said first number of capacitive loads having the charged state between said first number of capacitive loads and said second number of capacitive loads having the discharged state, thereby charging said second number of capacitive loads from ground to a preload voltage and discharging said first number of capacitive loads from said operating voltage to said preload voltage,charging said second number of capacitive loads having been charged to said preload voltage from said preload voltage to an intermediate voltage between said preload voltage and said operating voltage, andcharging said second number of capacitive loads having been charged to said intermediate voltage from said intermediate voltage to said operating voltage.
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Abstract
Method and apparatus for low-power charge transition in an I/O system of an integrated circuit comprising an interconnected linking of stepwise charging and charge recycling of capacitive loads. The I/O system according to the invention does not need additional pins for recycling capacitors, additional silicon area for on-chip capacitors, or additional power supplies. This I/O system achieves power savings of 20% to 30% of CV2 f.
7 Citations
9 Claims
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1. Method for low-power charge transition in an integrated-circuit I/O system which comprises a plurality of capacitive loads which convert between a charged state at an operating voltage and a discharged state at ground during each of operation cycles of the I/O system, wherein the operation cycles are predetermined by an external clock signal, and of which plurality of said capacitive loads a first number of capacitive loads having the charged state converts from the charged state to the discharged state at ground, and a second number of capacitive loads having the discharged state converts from the discharged state to the charged state at the operating voltage, the method comprising the steps of:
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sharing the charge of said first number of capacitive loads having the charged state between said first number of capacitive loads and said second number of capacitive loads having the discharged state, thereby charging said second number of capacitive loads from ground to a preload voltage and discharging said first number of capacitive loads from said operating voltage to said preload voltage, charging said second number of capacitive loads having been charged to said preload voltage from said preload voltage to an intermediate voltage between said preload voltage and said operating voltage, and charging said second number of capacitive loads having been charged to said intermediate voltage from said intermediate voltage to said operating voltage. - View Dependent Claims (2, 3, 4)
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5. Low-power I/O system of an integrated circuit for low-power charge transition in said I/O system, comprising
a plurality of capacitive loads which convert between a charged state at an operating voltage and a discharged state at ground during each of the operation cycles of said I/O system, wherein the operation cycles are predetermined by an external clock signal, and of which plurality of said capacitive loads a first number of capacitive loads having said charged state converts from said charged state to said discharged state at ground and a second number of capacitive loads having said discharged state converts from said discharged state to said charged state at the operating voltage, an intermediate power supply for providing an intermediate voltage, an operating power supply for providing an operating voltage, and per each capacitive load a transmission gate connected to said capacitive load for connecting said first number of capacitive loads to said second number of capacitive loads, an intermediate driver connected between said capacitive load and said intermediate power supply, an operating driver connected between said capacitive load and said operating power supply, and a control unit connected to said transmission gate, said intermediate driver and said operating driver, wherein the control units sequentially connect said second number of capacitive loads to said first number of capacitive loads through said transmission gates for a first duration by controlling the respective transmission gates, to said intermediate power supply for a second duration by controlling the respective intermediate drivers, and to said operating power supply for a third duration by controlling the respective operating drivers.
Specification