CAPACITANCE TO CODE CONVERTER WITH SIGMA-DELTA MODULATOR

• US 20180284928A1
• Filed: 04/18/2018
• Published: 10/04/2018
• Est. Priority Date: 11/14/2006
• Status: Active Grant

• Current Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Kremin, Viktor
• Granted Patent: US 10,928,953 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: H03M 11/02 Details

Abstract

Apparatuses and methods of converting a capacitance measured on a sense element to a digital value are described. One apparatus includes a modulator having a modulator capacitor, a sense element selectively coupled in a feedback loop of the modulator to operate as a switching capacitor. The apparatus also includes a first switch coupled between a voltage source and a first node of the switching capacitor and a second switch coupled between the first node of the switching capacitor and a first node of the modulator capacitor. The switching capacitor provides a charge current to the modulator capacitor via the second switch. The modulator measures a capacitance of the sense element and converts the measured capacitance to a digital code representing the capacitance.

Claims

1-20. -20. (canceled)

21. A capacitance-to-code converter comprising:

an input selectively couplable to a first sensing electrode;

an integrating circuit to integrate a signal on the input;

a first conversion circuit to convert the integrated signal to a first digital value, wherein the first digital value is representative of a self capacitance of the first sensing electrode; and

a second conversion circuit to convert the integrated signal to a second digital value, wherein the second digital value is representative of a mutual capacitance between the first sensing electrode and a second sensing electrode.

22. The capacitance-to-code converter of claim 21, wherein the signal is a voltage.

23. The capacitance-to-code converter of claim 22, wherein the voltage is applied to the first sensing electrode in a first phase of a switched-capacitor operation.

24. The capacitance-to-code converter of claim 21, wherein the signal is a current.

25. The capacitance-to-code converter of claim 24, wherein the current is induced on the first sensing electrode by a transmit signal on the second sensing electrode.

26. The capacitance-to-code converter of claim 21, wherein the first sensing electrode is substantially orthogonal to the second sensing electrode.

27. The capacitance-to-code converter of claim 21, wherein the first conversion circuit and the second conversion circuit share at least one component.

28. The capacitance-to-code converter of claim 21, wherein the first conversion circuit and the second conversion circuit operate at a first time and a second time, respectively.

29. The capacitance-to-code converter of claim 28, wherein the first conversion circuit and the second conversion circuit comprise substantially the same circuit elements, and wherein the circuit elements are configured to convert a self capacitance and a mutual capacitance in a first mode and a second mode, respectively.

30. A method comprising:

receiving a first signal on a first input coupled to a first sensing electrode;

integrating the first signal to generate a first integrated signal;

converting the first integrated signal to a first digital value, wherein the first digital value is representative of a self capacitance of the first sensing electrode; and

converting the first integrated signal to a second digital value, wherein the second digital value is representative of a mutual capacitance between the first sensing electrode and a second sensing electrode.

31. The method of claim 30, further comprising:

providing a second signal on the second input.

32. The method of claim 31, wherein the first signal received on the first input is a current induced by the second signal on the second input.

33. The method of claim 30, wherein the first signal is a voltage.

34. The method of claim 30, wherein converting the first integrated signal to the second digital value comprises:

reconfiguring at least one component of a conversion circuit for converting the first integrated signal to the first digital value.

35. A capacitance sensing device comprising:

a first capacitance sensing electrode;

a second capacitance sensing electrode;

an integrating circuit coupled to the first capacitance sensing electrode;

a first conversion circuit to convert an integrated signal from the first capacitance sensing electrode to a first digital value, wherein the first digital value is representative of a self capacitance of the first sensing electrode; and

a second conversion circuit to convert the integrated signal from the first capacitance sensing electrode to a second digital value, wherein the second digital value is representative of a mutual capacitance between the first capacitance sensing electrode and the second capacitance sensing electrode.

36. The capacitance sensing device of claim 35, wherein the first capacitance sensing electrode is substantially orthogonal to the second capacitance sensing electrode.

37. The capacitance sensing device of claim 35, wherein the first capacitance sensing electrode is substantially adjacent to the second capacitance sensing electrode.

38. The capacitance sensing device of claim 35, wherein the first conversion circuit and the second conversion circuit share at least one component.

39. The capacitance sensing device of claim 35, wherein the first conversion circuit and the second conversion circuit operate at a first time and a second time, respectively.

40. The capacitance sensing device of claim 39, wherein the first conversion circuit and the second conversion circuit comprise substantially the same circuit elements, and wherein the circuit elements are configured to convert a self capacitance and a mutual capacitance in a first mode and a second mode, respectively.