| CPC G01D 5/2053 (2013.01) [G01B 7/003 (2013.01)] | 11 Claims |
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1. Position sensing apparatus comprising:
a first member having an excitation conductive winding and a detection conductive winding formed thereon;
a second member having a resonant circuit formed thereon;
an integrated circuit comprising excitation signal generation and detection signal processing circuitry arranged to generate an alternating excitation signal at a resonant frequency of the resonant circuit and to process an alternating detection signal induced in the detection conductive winding as a result of a magnetic field generated by the alternating excitation signal flowing through the excitation conductive winding, wherein the excitation conductive winding and the detection conductive winding are arranged so that the detection signal varies in dependence on the relative position of the first and second member; and
phase-shift circuitry arranged to introduce a phase shift to one of the excitation signal and the detection signal such that the excitation signal output by the integrated circuit and the detection signal input to the detection circuit are in phase or in anti-phase with each other, the phase-shift circuitry comprising an impedance buffer circuit, a ninety-degree phase shift circuit, and an inductor arranged to control a frequency of the excitation signal output by the integrated circuit;
wherein the impedance buffer circuit is arranged between the inductor and the ninety-degree phase shift circuit, and the ninety-degree phase shift circuit is arranged between the impedance buffer circuit and the excitation conductive winding.
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