Patent ID: 9252691
Filing Date: 2016-02-02
CPC Classification: H02P

Claim Text:
1. A back-electromagnetic force (BEMF) sense system comprising a sense amplifier configured to measure an amplitude of a selected one of a plurality of phase voltages relative to a center tap voltage associated with a servo motor for the calculation of an associated BEMF voltage, the plurality of phase voltages being provided to the sense amplifier via a respective plurality of control nodes, the selected one of the plurality of phase voltages on a respective one of the control nodes being selected based on coupling the other of the plurality of control nodes associated with the other of the plurality of phase voltages to a voltage source configured to provide a predetermined voltage magnitude, wherein the BEMF sense system further comprises an input stage comprising a plurality of voltage dividers that are each associated with one of the plurality of phase voltages or the center tap voltage to provide the plurality of phase voltages on the respective plurality of control nodes to the sense amplifier at an adjusted magnitude relative to a reference voltage, and to provide the center tap voltage on a center tap control node to the sense amplifier at an adjusted magnitude relative to an output voltage of the sense amplifier corresponding to the amplitude of the selected one of a plurality of phase voltages relative to the center tap voltage, and wherein each of the plurality of voltage dividers comprises a switch configured to bypass at least one resistor associated with a respective one of the plurality of voltage dividers to implement gain control associated with the plurality of voltage dividers in response to a gain control signal.