System and method for differential eFUSE sensing without reference fuses
View Patent ↗A differential fuse sensing system includes a fuse leg configured for introducing a sense current through an electrically programmable fuse (eFUSE) to be sensed, and a differential sense amplifier having a first input node coupled to the fuse leg and a second node coupled to a reference voltage. The fuse leg further includes a current supply device controlled by a variable reference current generator configured to generate an output signal therefrom such that the voltage on the first input node of the sense amplifier is equal to the voltage on the second input node of the sense amplifier whenever the resistance value of the eFUSE is equal to the resistance value of a programmable variable resistance device included within the variable reference current generator.
1. A differential fuse sensing system, comprising;
a fuse leg configured for introducing a sense current through an electrically programmable fuse (eFUSE) to be sensed;
a differential sense amplifier having a first input node coupled to the fuse leg and a second node coupled to a reference voltage;
the fuse leg further comprising a current supply device controlled by a variable reference current generator configured to generate an output signal therefrom such that the voltage on the first input node of the sense amplifier is equal to the voltage on the second input node of the sense amplifier whenever the resistance value of the eFUSE is equal to the resistance value of a programmable variable resistance device included within the variable reference current generator; and
a first pair of isolation devices configured between the fuse leg and the first input node of the sense amplifier and a second pair of isolation devices configured between the reference voltage and the second input node of the sense amplifier, the first and second pair of isolation devices configured to establish, within the sense amplifiers, voltage difference proportional to the relative difference between the resistance of the eFUSE and a reference resistance defined by the digitally controlled, variable resistance device.
2. A differential fuse sensing system, comprising:
a fuse leg configured for introducing a sense current through an electrically programmable fuse (eFUSE) to be sensed;
a differential sense amplifier having a first input node coupled to the fuse leg and a second node coupled to a reference voltage;
the fuse leg further comprising a current supply device controlled by a variable reference current generator configured to generate an output signal therefrom such that the voltage on the first input node of the sense amplifier is equal to the voltage on the second input node of the sense amplifier whenever the resistance value of the eFUSE is equal to the resistance value of a programmable variable resistance device included within the variable reference current generator; and
wherein the sense amplifier further comprises a pair of ballast capacitors coupled to the first and second input nodes of the sense amplifier, the pair of ballast capacitors configured to retain a signal proportional to the relative difference between the resistance of the eFUSE and a reference resistance once the first and second input nodes of the sense amplifier are respectively decoupled from the fuse leg and reference voltage.
3. A differential fuse sensing system, comprising:
a fuse leg configured for introducing a sense current through an electrically programmable fuse (eFUSE) to be sensed;
a differential sense amplifier having a first input node coupled to the fuse leg and a second node coupled to a reference voltage;
the fuse leg further comprising a current supply device controlled by a variable reference current generator configured to generate an output signal therefrom such that the voltage on the first input node of the sense amplifier is equal to the voltage on the second input node of the sense amplifier whenever the resistance value of the eFUSE is equal to the resistance value of a programmable variable resistance device included within the variable reference current generator; and
a pair of restore devices configured to precharge the first and second input nodes of the sense amplifier to the reference voltage prior to sensing of the programmed state of the eFUSE.
4. The differential fuse sensing system of claim 1 , wherein the variable reference current generator further comprises:
a differential amplifier having the reference voltage as an inverting input thereto;
a mimic circuit configured to mimic devices of the fuse leg, wherein an internal node of the mimic circuit is coupled to a non-inverting input of the differential amplifier; and
a digitally controlled, variable resistance device, a resistance portion of which is configured within the mimic circuit;
wherein an output of the differential amplifier corresponds to the output signal used to control the current supply device of the fuse leg.
5. The differential fuse sensing system of claim 1 , further comprising And Or Invert (AOI) output stages coupled to the first and second input nodes of the sense amplifier, the AOI output stages configured to maintain a digital state of the eFUSE data therein, regardless of any subsequent fluctuations in the voltage values of the first and second input nodes of the sense amplifier and/or the reference voltage.
6. The differential fuse sensing system of claim 1 , further comprising a programming device coupled to the fuse leg, the programming device selectively configured to pass a programming current through the eFUSE.
7. The differential fuse sensing system of claim 2 , wherein the variable reference current generator further comprises:
a differential amplifier having the reference voltage as an inverting input thereto;
a mimic circuit configured to mimic devices of the fuse leg, wherein an internal node of the mimic circuit is coupled to a non-inverting input of the differential amplifier; and
a digitally controlled, variable resistance devices, a resistance portion of which is configured within the mimic circuits;
wherein an output of the differential amplifier corresponds to the output signal used to control the current supply device of the fuse leg.
8. The differential fuse sensing system of claim 2 , further comprising And Or Invert (AOI) output stages coupled to the first and second input nodes of the sense amplifier, the AOI output stages configured to maintain a digital state of the eFUSE data therein, regardless of any subsequent fluctuations in the voltage values of the first and second input nodes of the sense amplifier and/or the reference voltage.
9. The differential fuse sensing system of claim 2 , further comprising a programming device coupled to the fuse leg, the programming device selectively configured to pass a programming current through the eFUSE.
10. The differential fuse sensing system of claim 3 , wherein the variable reference current generator further comprises:
a differential amplifier having the reference voltage as an inverting input thereto;
a mimic circuit configured to mimic devices of the fuse leg, wherein an internal node of the mimic circuit is coupled to a non-inverting input of the differential amplifier; and
a digitally controlled, variable resistance device, a resistance portion of which is configured within mimic circuit;
wherein an output of the differential amplifier corresponds to the output signal used to control the current supply device of the fuse leg.
11. The differential fuse sensing system of claim 3 , further comprising And Or Invert (AOI) output stages coupled to the first and second input nodes of the sense amplifier, the AOI output stages configured to maintain a digital state of the eFUSE data therein, regardless of any subsequent fluctuations in the voltage values of the first and second input nodes of the sense amplifier and/or the reference voltage.
12. The differential fuse sensing system of claim 3 , further comprising a programming device coupled to the fuse leg, the programming device selectively configured to pass a programming current through the eFUSE.