A Noise-Immunity-Enhanced Analog Front-End for $36\times64$ Touch-Screen Controllers With 20-$\text{V}_{\text{PP}}$ Noise Tolerance at 100 kHz

Readout Circuits for Capacitive Sensors

“…Thus, not only the external noise but also the noise of the readout circuit, such as offset error, are removed. Recent studies used bandpass filters (BPFs) before demodulation and LPF to achieve higher noise-reduction performances [ 27 , 28 ]. This method can remove noises at different frequencies from signals; however, there is a limit in that it is difficult to remove noises that exist over the signal frequency.…”

“…However, depending on the code, the output signal may be saturated to output range. To prevent this from occurring, efficient orthogonal code was proposed [ 27 , 37 , 38 , 39 , 40 , 41 ]. As an additional problem, if the same code is repeatedly used for PDM, energy is concentrated at a specific frequency, and therefore, it may not be able to remove random noise along with the EMI problem properly.…”

“…Depending on the code, the output signal may become saturated beyond the output range as the signals for several sensors overlap. A more efficient orthogonal code was proposed [ 27 , 37 , 38 , 39 , 40 , 41 ]. PDM method may not be able to properly remove random noise along with the EMI problem if the same code is repeatedly used and concentrated at a specific frequency.…”

42‐1: A Controller IC for On‐display Touch and Multi‐Fingerprint Sensor

“…To achieve higher performance in given scanning time, Multi-Channel Driving transmitter (Tx) schemes have been proposed [1], [2]. The MCD schemes result in SNR improvement and external noise spreading effect.…”

“…Signal saturation can be a fatal drawback when the sensor system wants to increase MCD size to achieve better performance. Modified methods have tried to mitigate the column offset effect [1]- [2], but they could not be a fundamental solution because the offset is always larger than that of SD. Thus, we propose a new MCD method to overcome the problem.…”