Sensing circuit, corresponding amplifier, apparatus and method
AssigneeSTMicroelectronics S.r.l.
InventorsStefano Ramorini, Alberto Cattani, Germano Nicollini, Alessandro Gasparini
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Abstract
A switching amplifier, such as a Class D amplifier, includes a current sensing circuit. The current sensing circuit is formed by replica loop circuits that are selectively coupled to corresponding output inverter stages of the switching amplifier. The replica loop circuits operated to produce respective replica currents of the output currents generated by the output inverter stages. A sensing circuitry is coupled to receive the replica currents from the replica loop circuits and operates to produce an output sensing signal as a function of the respective replica currents.
Claims30
A circuit, comprising:
- a current mirror comprising an output drive transistor having a source node and a drain node and a current sensing transistor having a source node and a drain node;
- a differential amplifier having a first input coupled to the drain node of the output drive transistor and a second input coupled to the drain node of the current sensing transistor;
- a further transistor having a gate node coupled to an output of the differential amplifier, a source node coupled to the drain node of the current sensing transistor and a drain node generating a replica current output;
- and
- an auto-zero circuit, comprising:
- a first switched capacitor circuit path coupled between the drain node of the output drive transistor and the first input of the differential amplifier;
- and
- a second switched capacitor circuit path coupled between the drain node of the output drive transistor and the first input of the differential amplifier.
A circuit, comprising:
- a current mirror comprising an output drive transistor having a source node and a drain node and a current sensing transistor having a source node and a drain node;
- a differential amplifier having a first input coupled to the drain node of the output drive transistor and a second input coupled to the drain node of the current sensing transistor;
- a further transistor having a gate node coupled to an output of the differential amplifier, a source node coupled to the drain node of the current sensing transistor and a drain node generating a replica current output;
- and
- an auto-zero circuit, comprising:
- a capacitor having a first terminal and a second terminal, wherein the second terminal is coupled to the second input of the differential amplifier;
- a first switch coupled between the first input of the differential amplifier and the first terminal of the capacitor;
- a second switch coupled between the second terminal and the drain node of the current sensing transistor;
- and
- a third switch coupled between the first terminal and the drain node of the current sensing transistor.
Dependencies are inferred from the claim text.