초록 ▼

A BEMF detector and method detect the BEMF of a three-phase motor using a fully differential detection system. The motor has a first coil coupled between a first coil tap and a center tap, a second coil coupled between a second coil tap and the center tap, and a third coil coupled between a third co

A BEMF detector and method detect the BEMF of a three-phase motor using a fully differential detection system. The motor has a first coil coupled between a first coil tap and a center tap, a second coil coupled between a second coil tap and the center tap, and a third coil coupled between a third coil tap and the center tap. The BEMF detector includes a differential amplifier having first and second inputs and first and second outputs, with the first input being coupled to one of the coil taps and the second input being coupled to the center tap. The BEMF detector also includes a comparator having first and second inputs coupled respectively to the first and second outputs of the differential amplifier and an output at which a BEMF signal is produced that is related to the BEMF of the motor. The differential amplifier may be part of an anti-alias filter structured to fix to a known stable value a common mode at the outputs of the differential amplifier. The BEMF detector also may include one or more fully differential filters positioned between the differential amplifier and the comparator to reduce noise and smooth the BEMF signal output by the comparator. One of the filters can be a linear phase, switched capacitor filter with a stable cutoff frequency.

대표청구항 ▼

[ What is claimed is:] [1.] A BEMF detector for detecting BEMF of a three-phase motor having a first coil coupled between a first coil tap and a center tap, a second coil coupled between a second coil tap and the center tap, and a third coil coupled between a third coil tap and the center tap, the B

[ What is claimed is:] [1.] A BEMF detector for detecting BEMF of a three-phase motor having a first coil coupled between a first coil tap and a center tap, a second coil coupled between a second coil tap and the center tap, and a third coil coupled between a third coil tap and the center tap, the BEMF detector comprising:a differential amplifier having first and second inputs and first and second outputs, the first input being coupled to one of the coil taps and the second input being coupled to the center tap; anda comparator having first and second inputs coupled respectively to the first and second outputs of the differential amplifier and an output at which a BEMF signal is produced that is related to the BEMF of the motor.