Patent ID: 8159474
Filing Date: 2012-04-17
Classification: G06F

Abstract:
1. An untethered stylus configured to cooperate with a location sensor, the location sensor configured to generate a drive signal, the stylus comprising: a housing; transceiver circuitry disposed in the housing, the transceiver circuitry configured to receive the drive signal and transmit a stylus signal for reception by the location sensor; energy circuitry disposed in the housing and energized by the drive signal; and a reference frequency generator disposed in the housing and coupled to the transceiver circuitry and energy circuitry, the reference frequency generator configured to generate a plurality of reference frequencies based on a source frequency of the drive signal, the plurality of reference frequencies indicative of a plurality of stylus states and synchronized to the source frequency of the drive signal, wherein the transceiver circuitry is configured to mix all of the plurality of reference frequencies with the stylus signal at a same point in time, and wherein the reference frequency generator comprises at least one of an even harmonic generator circuit, an odd harmonic generator circuit, a full wave rectifier, and a square wave generator.