Abstract: Method, apparatus, and systems for roll angle estimation for an input/gesture device (IGD) are disclosed. The method includes estimating a first axis vector of the input/gesture device (IGD) relative to the surface of the mobile device (MD), as a first frame of reference, using readings from a first type of sensor; and estimating the first axis vector of the IDG relative to a different, second frame of reference using a gyroscope integration of readings from the 3-axis gyroscope. The method further includes aligning the first axis vector of the IDG in the first frame of reference with the first axis vector of the IDG in the second frame of reference; minimizing a change in the alignment of the first axis vectors between the first frame of reference and the second frame of reference; and determining the roll angle of the IDG relative to the surface of the MD.

Abstract: A programmable voltage reference circuit that includes a current-to-voltage converter circuit, a voltage-to-current converter circuit, and a floating gate. The current-to-voltage converter circuit has two current input terminals and a voltage output terminal. The voltage-to-current converter circuit has two voltage input terminals and two current output terminals. The two current output terminals are each coupled to a corresponding current input terminal of the current-to-voltage converter circuit. A floating gate device has one terminal coupled to a fixed voltage supply, and one terminal coupled to an input terminal of the voltage-to-current converter. The other input terminal of the voltage-to-current converter is coupled to the voltage reference output terminal of the programmable voltage reference circuit. Also, the voltage output terminal of the current-to-voltage converter circuit is coupled to the negative voltage input terminal of the voltage-to-current input circuit.