SUPERHETERODYNE PEN STIMULUS SIGNAL RECEIVER

摘要

A superheterodyne stylus signal receiver for detecting a stylus stimulation signal from a stylus is provided. The stylus signal receiver can be configured to convert the touch signal into an intermediate frequency signal having a frequency that is less than that of the touch signal. In some examples, a hardware-implemented I-phase demodulator can be used to convert the touch signal into the intermediate frequency signal. The receiver can be further configured to perform IQ demodulation on the intermediate frequency signal at the intermediate frequency signal's lower frequency. In some examples, the IQ demodulation can be performed in firmware.

主权项

1: A signal receiver comprising:
down-converting circuitry coupled to receive a touch signal representative of a touch event on a touch sensor, wherein the touch signal is generated in response to a stylus stimulation signal from a stylus device, and wherein the down-converting circuitry is operable to convert the touch signal into an intermediate frequency signal having an intermediate frequency that is less than a frequency of the touch signal; and a processor operable to demodulate the intermediate frequency signal to determine an amplitude of the touch signal.