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US 5,969,554 AGranted
Multi-function pre-driver circuit with slew rate control, tri-state operation, and level-shifting
AssigneeInternational Business Machines Corporation
InventorsFrancis H. Chan, Douglas Willard Stout
Life of this patent
Estimating the term…
Abstract
A pre-driver circuit in an I/O circuit for an integrated circuit performs the combined functions of voltage level shifting, slew rate control, and tri-state capability, in a single circuit to avoid additional delay caused by implementing any combination of these functions in two or more circuits.
Claims16
An I/O circuit for an integrated circuit (IC) chip, comprising:
- a pre-driver circuit including:
- an input for receiving an input signal having a first voltage range;
- an output for transmitting an output signal corresponding to said input signal, said output signal having a second voltage range;
- a level shifter circuit receiving said input signal for shifting said first voltage range of said input signal to said second voltage range of said output signal, and coupled directly to the output for providing said output signal to the output;
- a slew rate control circuit coupled directly to the output in parallel with the level shifter circuit for controlling a slew rate of said output signal;
- and
- a tri-state circuit coupled to both the level shifter circuit and to the slew rate control circuit for activating said level shifter circuit and said slew rate control circuit in response to a tri-state input signal.
4 more elements
A pre-driver circuit comprising:
- an input for receiving an input signal having a first voltage range;
- an output for transmitting an output signal corresponding to said input signal, said output signal having a second voltage range;
- a level shifter circuit receiving said input signal for shifting said first voltage range of said input signal to said second voltage range of said output signal, and coupled directly to the output for providing said output signal to the output;
- a slew rate control circuit coupled directly to the output in parallel with the level shifter circuit for controlling a slew rate of said output signal;
- and
- a tri-state circuit coupled to both the level shifter circuit and to the slew rate control circuit for activating said level shifter circuit and said slew rate control circuit in response to a tri-state input signal.
3 more elements
An I/O circuit for an integrated circuit comprising:
- a pre-driver circuit including:
- an input for receiving an input signal having a first voltage range;
- an output for transmitting an output signal in response to said input signal, said output signal having a second voltage range;
- slew rate control means for controlling the slew rate of said output signal;
- tri-state means for activating said pre-driver circuit in response to a tri-state input signal;
- and
- level shifter means for changing said first voltage range of said input signal to said second voltage range of said output signal;
- and
- wherein said level shifter means includes:
- a first transistor having a first contact coupled to a first voltage source, a second contact coupled to said output, and a third contact;
- a second transistor having a first contact coupled to said first voltage source, a second contact coupled to said third contact of said first transistor, and a third contact;
- a third transistor having a first contact coupled to said third contact of said first transistor and to said second contact of said second transistor, a second contact, and a third contact coupled to a second voltage source;
- and
- a fourth transistor having a first contact coupled to said second contact of said third transistor, a second contact coupled to ground, and a third contact for receiving the input signal.
11 more elements
Dependencies are inferred from the claim text.