Fully differential operational amplifier common mode current sensing feedback
AssigneeSTMicroelectronics S.r.l.
InventorsMarco Zamprogno, Simone Zezza, Pasquale Flora
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Abstract
A method and apparatus for sensing a common mode feedback current are provided. The common mode feedback current may flow through a common mode resistive divider of a piezoresistive bridge. A first current mirror mirrors the common mode feedback current and provides a first mirrored common mode current. A current aggregation stage receives the first mirrored common mode current and determines a bridge current of the piezoresistive bridge based on the first mirrored common mode feedback current. A second current mirror may be used to mirror the first current mirror before determining the bridge current.
Claims20
A device, comprising:
- a common mode resistive divider including first and second resistances that are coupled in series;
- a piezoresistive bridge;
- a first current mirror, coupled to the common mode resistive divider, configured to mirror a common mode current flowing through the common mode resistive divider and provide a first mirrored common mode current, the first current mirror including a first feedback transistor that is coupled in series with the first and second resistances and that has the common mode current flowing therethrough;
- and
- a current aggregation stage configured to receive the first mirrored common mode current and determine a bridge current of the piezoresistive bridge based on the first mirrored common mode feedback current.
A method, comprising:
- mirroring, by a first current mirror, a common mode current flowing through a common mode resistive divider for a piezoresistive bridge to produce a first mirrored common mode current, the common mode resistive divider including first and second resistances that are coupled in series, and the first current mirror including a first feedback transistor that is coupled in series with the first and second resistances and that has the common mode current flowing therethrough;
- and
- determining a bridge current of the piezoresistive bridge based on the first mirrored common mode feedback current.
A micro-electromechanical systems (MEMS) system, comprising:
- a first current mirror, coupled to a common mode resistive divider of a piezoresistive bridge, configured to mirror a common mode current flowing through the common mode resistive divider and provide a first mirrored common mode current, the common mode resistive divider including first and second resistances that are coupled in series, and the first current mirror including a first feedback transistor that is coupled in series with the first and second resistances and that has the common mode current flowing therethrough;
- a current aggregation stage configured to receive the first mirrored common mode current and determine a bridge current of the piezoresistive bridge based on the first mirrored common mode feedback current;
- and
- a piezoresistive bridge sensitivity compensation stage configured to receive the bridge current and compensate a sensitivity of a MEMS device based on the bridge current.
Dependencies are inferred from the claim text.