Common-gate comparator and fuse reader

A system for determining a state of one or more fuses, the system comprising:

• a first FET device;
• a first switch configured to selectively couple drain and gate nodes of the first FET device based on a first switch control signal;
• a second switch configured to selectively couple a source node of the first FET device to a reference signal source;
• and
• a capacitor coupled to the gate node of the first FET device;
• wherein the capacitor stores information about a reference signal when the first switch couples the drain and gate nodes of the first FET device and the reference signal is received via the second switch at the source node of the first FET device;
• and
• wherein an output signal at the drain node of the first FET device indicates a magnitude relationship between a second input signal and the reference signal when the first switch decouples the drain and gate nodes of the first FET device, the second switch decouples the source node of the first FET from the reference signal source, and the source node of the first FET device receives the second input signal via a third switch;
• wherein the second input signal inicates a state of a first fuse.

A method for determining a relationship between a first input signal and a second input signal using a common-gate PET device, the method comprising:

• in a reference phase:
• coupling drain and gate nodes of the FET device using a first switch, the first switch responsive to an auto-zero signal;
• coupling an input source node of the FET device to receive the first input signal using a second switch, and storing information about a reference voltage using a capacitor coupled to the gate node of the FET device;
• and
• in a read phase:
• decoupling the drain and gate nodes of the FET device using the first switch;
• coupling the input source node of the FET device to receive the second input signal using a third switch;
• and
• while the second input signal is applied to the input source node of the PET device, receiving an output signal from the drain node of the PET device, wherein a magnitude of the output signal indicates a magnitude relationship between the first and second input signals.