This document introduces mTouch capacitive touch sensing technology. It discusses how mTouch works using capacitive sensing without mechanical buttons. The main components are a touch sensor and relaxation oscillator circuit, which uses frequency measurement to detect changes in capacitance from a finger touch on the sensor. The sensor is constructed with copper pads on a printed circuit board with a glass or plastic covering.

4. Overview of mTouch™ Capacitive Touch Sensing

5. Relaxation Oscillator Circuit

6. Frequency Measurement

7. Equation of Capacitance

12. Equivalent Circuit

13. RC Circuit Without finger introduced With finger introduced Figure 1 Figure 2

14. Oscillator Circuit

15. Oscillator Circuit cont’d

16. Oscillator Circuit cont’d

17. Oscillator Circuit cont’d

18. Oscillator Operation

19. Oscillator Operation cont’d

20. Oscillator Operation cont’d

21. Oscillator Operation cont’d

22. Oscillator Operation cont’d

23. Oscillator Operation cont’d

24. Frequency Measurement

25. Frequency Measurement cont’d

26. Frequency Measurement cont’d

27. Frequency Measurement cont’d