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Capacitive touch-screen technology introduces new concepts to user interfaces, such as multi-touch, pinch zoom-in/out gestures, thus expanding the smartphone market. However, capacitive touch-screen technology still suffers from performance degradation like a low frame scan rate and poor accuracy, etc. One of the key performance factors is the immunity to external noise, which intrudes randomly into the touch-screen system. HUM, display noise, and SMPS are such noise sources. The main electrical power source produces HUM, one of the most important sources of noise, which has a 50 or 60Hz component. Display noise is emitted when an LCD or OLED is driven by the internal timing controller, which generates the driving signal in the tens of kHz range. The touch performance of On-Cell or In-Cell touch displays is seriously affected by this kind of noise, because the distance between the display pixel layer and the capacitive touchscreen panel is getting smaller. SMPS is another noise source that ranges up to 300kHz. The charger for a smart-phone, the USB port in a computer, a tri-phosphor fluorescent light bulb are all examples of sources of SMPS. There have been many attempts to remove such noise. Amplitude modulation with frequency hopping is proposed in [1]. However, when the noise environment changes, this method needs recalibration, resulting in non-constant touch response time. Another method tries to filter the noise from the display [2], but it does not remove other noise sources like HUM or SMPS.A time-interleaved sensing method is adopted in conventional noise-reduction techniques. Figure 22.5.1 shows how to do time-interleaved sensing on a 2D matrix of the mutual capacitance C M , which exists on the cross-section point, a node, of a TX electrode and an RX electrode. The access time T S to measure C M of each node is stretched longer to reduce the noise. However, as more sensing nodes are added with bigger display size, the time-interleaved sensing method cannot avoid a degradation of the frame scan rate. In this paper, we propose a code-division multiple-sensing (CDMS) method to solve all of the above problems. By Parseval's theorem, to get higher SNR for the touch-screen system with a wideband noise distribution, the power spectral density of the signal should be higher, which inevitably necessitates longer access time. Thus there is trade-off between SNR and access time in the time-interleaved sensing method. However, this can be overcome by adopting a CDMA technique, which is a well-established method in RF communication systems. The CDMS method can emit higher excitation signal power than the time-interleaved method does, because it allows driving multiple TX electrodes simultaneously in a given period of time. Through the simultaneous multiple-stimulus-and-sensing characteristic of CDMA, a high frame scan rate can be achieved with low noise. Figure 22.5.2 shows the system block diagram to sense the touch-screen panel capacitance matrix composed of 30 TX electrodes and 24 RX electrodes. In the system bl...

We propose a pipelined division architecture for low-power ECC applications, which is based on partialdivision on group basis and lookahead technique exploiting the linearity in finite field arithmetic. The throughput is one division per clock regardless of the degree of the dividend polynomial. The salient feature of this architecture is that it leads very low power-delay product. To verify the relative performance of the proposed division architecture over the conventional one using LFSR, three RS and BCH code applications were fabricated using 0.8µm double metal CMOS technology. Experimental results show about 32, 65, 67 times improvement in power consumption compared with conventional one using LFSR.

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