Differential capacitance sense amplifier
AssigneeRaytheon Company
InventorsMark V. Martin, John J. Drab
Life of this patent
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Abstract
A differential capacitance sense amplifier capable of measuring a small difference-signal capacitance in the presence of circuit mismatches and large unequal interconnect capacitances. The sense amplifier includes three sections: a common-mode section applies a ‘read’ voltage to two capacitors in a manner that rejects unequal interconnect capacitance, a difference-mode section generates a signal proportional to the capacitance difference between the two capacitors, and an offset-canceling section compensates for circuit mismatches in the difference-mode section. The amplifier can be adapted for use as a sense amplifier for a ferroelectric differential capacitance memory unit.
Claims36
A differential capacitance sense amplifier, comprising:
- a transconductance common mode amplifier for applying a ‘read’ voltage to a pair of capacitors in a manner that rejects unequal interconnect capacitance, and
- a differential amplifier for generating a signal proportional to the capacitance difference between a first capacitor of the pair of capacitors and a second capacitor of the pair of capacitors.
A differential capacitance sense amplifier comprising:
- a common-mode section for applying a ‘read’ voltage to a pair of capacitors in a manner that rejects unequal interconnect capacitance,
- a difference-mode section for generating a signal proportional to the capacitance difference between a first capacitor of the pair of capacitors and a second capacitor of the pair of capacitors, and
- an offset-canceling section to compensate for circuit mismatches in the difference-mode section.
A method for using a differential capacitance sense amplifier to read a differential capacitance between a first capacitor of a pair of capacitors and a second capacitor of a pair of capacitors, comprising:
- placing the differential capacitance sense amplifier into a reset mode, wherein
- a read voltage is applied to a (+) input of a transconductance common mode amplifier,
- an output of the common mode amplifier is shorted to a bitline, the bitline having a first parasitic capacitance and being connected to a first (−) input of the common mode amplifier,
- the output of the common mode amplifier is shorted to a bitlinebar, the bitlinebar having a second parasitic capacitance and being connected to a second (−) input of the common mode amplifier,
- the bitline is connected to a first (+) input of a differential amplifier,
- the bitlinebar is connected to a first (−) input of a differential amplifier,
- a bitline switch for connecting the bitline to the first capacitor is in the open position,
- a bitlinebar switch for connecting the bitlinebar to the second capacitor is in the open position, the first capacitor is shorted through a first shorting-switch,
- and the second capacitor is shorted through a second shorting-switch.
Dependencies are inferred from the claim text.