Power frequency interference resistant receiving circuit and capacitance pen

Abstract

The invention discloses an anti-power-frequency-interference receiving circuit and a capacitance stylus, the anti-power-frequency-interference receiving circuit comprises a high-pass filter circuit, the high-pass filter circuit comprises a charge amplification circuit and a resistor, a signal input end of the charge amplification circuit receives a DSSS signal sent by a touch terminal and is used for carrying out charge amplification on the DSSS signal and outputting the DSSS signal, and a signal output end of the charge amplification circuit is used for outputting the DSSS signal; the charge amplifying circuit is provided with a feedback branch; the first end of the resistor is connected with the first end of the feedback branch, and the second end of the resistor is connected with the second end of the feedback branch; the input end of the voltage amplification circuit is connected with the output end of the charge amplification circuit, and the voltage amplification circuit is used for amplifying and outputting the input voltage; according to the invention, the original charge amplification circuit of the receiving circuit is converted into the capacitance pen capable of resisting power frequency interference by adding the resistor, and the size of the receiving circuit is not greatly changed, so that the occupation of the internal space of the capacitance pen is reduced as much as possible while the power frequency interference is suppressed.

Description

technical field [0001] The invention relates to the technical field of capacitive pens, in particular to a receiving circuit and a capacitive pen against power frequency interference. Background technique [0002] At present, capacitive pens are generally powered by batteries and do not need to be grounded. When writing normally, the hand of the person will hold the capacitive pen, and the human being, as a conductor with relatively large impedance, can still transfer the power frequency interference signal to the capacitive pen from the human hand. The receiving circuit of the capacitive pen normally couples the received modulated signal as the DSSS modulated signal sent by the screen, its frequency range is 50-200KHz, and the signal voltage coupled to the pen tip is within 1V. The frequency of the power frequency interference signal is generally around 50Hz. When the oscilloscope probe is suspended in the air, a strong power frequency signal can be measured; when the huma...

AI Technical Summary

Problems solved by technology

[0003] When the user uses the capacitive pen, the power frequency interference signal will be transmitted to the capacitive pen by hand, superimposed with the DSSS signal, covering the DSSS signal, thus affecting the demodulation of the RX signal by the capacitive pen

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