72 dB SNR, 240 Hz Frame Rate Readout IC With Differential Continuous-Mode Parallel Architecture for Larger Touch-Screen Panel Applications

This paper presents a mutual capacitive touch screen panel (TSP) readout IC (ROIC) with a differential continuousmode parallel operation architecture (DCPA). The proposed architecture achieves a high product of signal-to-noise ratio (SNR) and frame rate, which is a requirement of ROIC for large-sized TSP. DCPA is accomplished by using the proposed differential sensing method with a parallel architecture in a continuousmode. This architecture is implemented using a continuous-type transmitter for parallel signaling and a differential-architecture receiver. A continuous-type differential charge amplifier removes the common-mode noise component, and reduces the self-noise by the band-pass filtering effect of the continuous-mode charge amplifier. In addition, the differential parallel architecture cancels the timing skew problem caused by the continuous-mode parallel operation and effectively enhances the power spectrum density of the signal. The proposed ROIC was fabricated using a 0.18-μm CMOS process and occupied an active area of 1.25 mm2. The proposed system achieved a 72 dB SNR and 240 Hz frame rate with a 32 channel TX by 10 channel RX mutual capacitive TSP. Moreover, the proposed differential-parallel architecture demonstrated higher immunity to lamp noise and display noise. The proposed system consumed 42.5 mW with a 3.3-V supply.

[1]  G. Fedder,et al.  A Low-Noise Low-Offset Capacitive Sensing Amplifier for a 50-g = Hz Monolithic CMOS MEMS Accelerometer , 2004 .

[2]  Hyungcheol Shin,et al.  A 55dB SNR with 240Hz frame scan rate mutual capacitor 30×24 touch-screen panel read-out IC using code-division multiple sensing technique , 2013, 2013 IEEE International Solid-State Circuits Conference Digest of Technical Papers.

[3]  Mohammad Maymandi-Nejad,et al.  Continuous time common mode feedback technique for sub 1 V analogue circuits , 2002 .

[4]  Franklin Bien,et al.  Highly improved SNR differential sensing method using parallel operation signaling for touch screen application , 2014, 2014 IEEE Asian Solid-State Circuits Conference (A-SSCC).

[5]  Oh-Kyong Kwon,et al.  A touch controller using differential sensing method for on-cell capacitive touch screen panel systems , 2011, IEEE Transactions on Consumer Electronics.

[6]  Chul-Sang Jang,et al.  A Fast and Energy Efficient Single-Chip Touch Controller for Tablet Touch Applications , 2013, Journal of Display Technology.

[7]  Deog-Kyoon Jeong,et al.  A Reconfigurable 40-to-67 dB SNR, 50-to-6400 Hz Frame-Rate, Column-Parallel Readout IC for Capacitive Touch-Screen Panels , 2014, IEEE Journal of Solid-State Circuits.

[8]  Bernhard E. Boser,et al.  A three-axis micromachined accelerometer with a CMOS position-sense interface and digital offset-trim electronics , 1999, IEEE J. Solid State Circuits.

[9]  Joo-Hyeon Lee,et al.  A capacitive touch controller robust to display noise for ultrathin touch screen displays , 2012, 2012 IEEE International Solid-State Circuits Conference.

[10]  Gyu-Hyeong Cho,et al.  A Noise-Immune High-Speed Readout Circuit for In-Cell Touch Screen Panels , 2013, IEEE Transactions on Circuits and Systems I: Regular Papers.

[11]  Gyu-Hyeong Cho,et al.  A highly noise-immune touch controller using Filtered-Delta-Integration and a charge-interpolation technique for 10.1-inch capacitive touch-screen panels , 2013, 2013 IEEE International Solid-State Circuits Conference Digest of Technical Papers.

[12]  G.K. Fedder,et al.  A low-noise low-offset capacitive sensing amplifier for a 50-/spl mu/g//spl radic/Hz monolithic CMOS MEMS accelerometer , 2004, IEEE Journal of Solid-State Circuits.

[13]  E. Sanchez-Sinencio,et al.  A continuous-time sigma-delta modulator with 88-dB dynamic range and 1.1-MHz signal bandwidth , 2004, IEEE Journal of Solid-State Circuits.

[14]  Franklin Bien,et al.  Dynamic range enhanced readout circuit for a capacitive touch screen panel with current subtraction technique , 2014, ESSCIRC 2014 - 40th European Solid State Circuits Conference (ESSCIRC).

[15]  Edgar Sanchez-Sinencio,et al.  Multipath common-mode feedback scheme suitable for high-frequency two-stage amplifiers , 2006 .

[16]  John Choma,et al.  A continuous-time common-mode feedback circuit (CMFB) for high-impedance current-mode applications , 2000 .

[17]  Hyungcheol Shin,et al.  12.5 2D Coded-aperture-based ultra-compact capacitive touch-screen controller with 40 reconfigurable channels , 2014, 2014 IEEE International Solid-State Circuits Conference Digest of Technical Papers (ISSCC).

[18]  Oh-Kyong Kwon,et al.  A highly area-efficient controller for capacitive touch screen panel systems , 2010, IEEE Transactions on Consumer Electronics.

[19]  T. Kwan,et al.  An adaptive analog continuous-time CMOS biquadratic filter , 1991 .

[20]  Franklin Bien,et al.  Algorithm for improving snr using high voltage and differential manchester code for capacitive touch screen panel , 2014 .

[21]  Shigetaka Takagi,et al.  Common-mode feedback circuit with differential-difference amplifier , 1994 .

[22]  Yoon-Kyung Choi,et al.  A fully-differential capacitive touch controller with input common-mode feedback for symmetric display noise cancellation , 2014, 2014 Symposium on VLSI Circuits Digest of Technical Papers.