Fuse circuit with feedback disconnect
AssigneeSGS-Thomson Microelectronics S.A.
InventorDavid C. McClure
Life of this patent
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Abstract
A method and circuit are disclosed which can be incorporated into any circuitry which uses fused algorithms to control the circuitry. Specifically, the invention may be incorporated into an integrated circuit device by way of a circuit that controls the coupling of an input signal to an output. Careful placement of a fuse or similarly functioning element in the circuit, permits the output of said circuit to be reliably set to a desired logic state. Specifically, when the fuse element is opened, a portion of the feedback path is disconnected, thereby preventing feedback in the direction of the unwanted logic state. The present invention enables construction of a fuse circuit which latches a desired logic state with stable performance and no layout area or speed degradation.
Claims30
A circuit for defining a logic state in an integrated circuit, comprising:
- a first logic element having an input and an output;
- a fuse element having a first terminal and a second terminal wherein the first terminal is coupled to the input of said first logic element, said fuse element being selectively configured in a conducting or a non-conducting state between said first and second terminals;
- a first transistor having a control electrode and having a conduction path coupled between a first voltage source and the input of said first logic element, said conduction path of said first transistor being enabled or disabled responsive to the output of said first logic element;
- and
- a second transistor having a control electrode and having a conduction path coupled between the second terminal of said fuse element and a second voltage source such that said second voltage source is decoupled from said input of said first logic element if said fuse element is in said non-conductive state, said conduction path of said second transistor being enabled or disabled responsive to the output of said first logic element.
A method for isolating a signal path, comprising the steps of:
- buffering an output signal with a circuit;
- selectively configuring a fuse element between an input terminal and an input to said circuit in an enabled or a disabled state;
- connecting a first voltage, in response to the output signal, to the input of the circuit;
- and
- connecting a second voltage, in response to the output signal, to the input terminal, such that the input terminal is decoupled from the input of said circuit if said fuse element is in a disabled state and is coupled to the input of said circuit if said fuse element is in an enabled state.
A circuit for isolating a signal path, comprising:
- circuit means for buffering an output signal;
- fuse means for selectively opening a connection between an input terminal and an input to said circuit means;
- first transistor switch means for connecting a first voltage, in response to the output signal applied thereto, to the input of the circuit means;
- and
- second transistor switch means for connecting a second voltage, in response to the output signal applied thereto, to the input to said circuit means, said second voltage being decoupled from the input terminal if said fuse means is in an open state.
A circuit for defining a logic state in an integrated circuit, comprising:
- a first logic element having an input and an output;
- a fuse element having a first terminal and a second terminal wherein the first terminal is coupled to the input of said first logic element, said fuse element being selectively configured in a conducting or a non-conducting state between said first and second terminals;
- circuitry for receiving a logic signal at said first terminal;
- a first transistor having a control electrode and having a conduction path coupled between a first voltage source and the input of said first logic element, said conduction path of said first transistor being enabled or disabled responsive to the output of said first logic element;
- and
- a second transistor having a control electrode and having a conduction path coupled between the second terminal of said fuse element and a second voltage source such that said second voltage source is decoupled from said input of said first logic element if said fuse element is in said non-conductive state, said conduction path of said second transistor being enabled or disabled responsive to the output of said first logic element.
Dependencies are inferred from the claim text.