Design Of Analog Front-end Interface For Capacitive Multi-touch Chip

With the publish of iPhone, capacitive multi-touch technology research has presenta phenomenon as hundreds of flowers blossom. While the key technology of capacitivemulti-touch almost are controlled by overseas company, and domestic such researchinstitutions are few and the technology is lack of advance, so the research of capacitivemulti-touch technology not only can break the overseas company monopoly but also hastremendous market value. Since capacitive multi-touch chip is mainly used onconsumer electronics, it requires touch control system more and more on anti noise,power consumption and cost.Based on analyzing the basic principles of capacitive touch panel and the methodof noise suppression, studying the system architecture and control principle of touchpanel controller, discussing practical electronic technology for low power and testabilitydesign, this master’s degree thesis proposes analog front-end interface circuit to solvethe above problems.This article has mainly discussed analog front end interface circuit to improve antinoise by supporting frequency hopping, noise testing and digital filter; through gatingclock technology to reduce power consumption; through time division multiplex toreduce the die size; through asynchronous reset synchronization processing to solve themetastability; through Full Handshaking to solve crossing clock domain data transmit;and also consider to content testing design requirements in circuital design.This article includes reset signal processing, ADC control, sensor channel control,drive control and data processing. By using Verilog language to design code, functionalsimulation result shows that it generates all kinds of scanning frequencies according tothe demand of frequency hopping; it can properly generate charge-amplifier reset signal;it can properly transmit data in different clock domains. Power analysis has been doafter auto place&route, the result shows it can reduce power conmumption by16.7%.The chip can better anti RF noise, charging noise and LCD noise.