Granted Patent B2

US 10,180,763 · App. 15/966,169 · Granted Jan 15, 2019

Inventors: Terje Saether (Trondheim, NO); Carl Olof Fredrik Jonsson (Gavle, SE)

Assignee: Atmel Corporation

G06F3/044G06F3/0412G06F3/0416G06F3/041

Abstract

Claims (50)

1. A method comprising:

driving, by a first driver circuit, a current through an electrode of a plurality of electrodes of a touch sensor, the first driver circuit comprising a first operational transconductance amplifier and a first current mirror coupled to the first operational transconductance amplifier; and

detecting, by a sensing system coupled to the first driver circuit, a touch based on a change in capacitance at the electrode of the plurality of electrodes of the touch sensor, wherein:

a second current mirror is coupled to the sensing system;

a first switch is coupled to the first current mirror;

a second switch is coupled to the first current mirror and to the first operational transconductance amplifier;

a third switch is coupled to the first operational transconductance amplifier and to the second current mirror;

a fourth switch is coupled to the second current mirror;

a fifth switch is coupled to the first operational transconductance amplifier;

a sixth switch is coupled to the first operational transconductance amplifier; and

a seventh switch is coupled to the first operational transconductance amplifier, the first current mirror, and the second current mirror.

2. The method of claim 1 , further comprising:

closing the second switch, the fourth switch, and the seventh switch when a rate of change of an input voltage to the first driver circuit is positive; and

opening the first switch, the third switch, the fifth switch, and the sixth switch when the rate of change of the input voltage to the first driver circuit is positive.

3. The method of claim 1 , wherein:

the first switch and the fourth switch are closed when a rate of change of an input voltage to the first driver circuit is zero; and

the second switch, the third switch, and the seventh switch are open when the rate of change of the input voltage to the first driver circuit is zero.

4. The method of claim 1 , further comprising:

closing the first switch, the third switch, and the seventh switch when a rate of change of an input voltage to the first driver circuit is negative; and

opening the second switch, the fourth switch, the fifth switch, and the sixth switch when the rate of change of the input voltage to the first driver circuit is negative.

5. A method comprising:

driving, by a first driver circuit, a current through an electrode of a plurality of electrodes of a touch sensor, the first driver circuit comprising a first operational transconductance amplifier and a first current mirror coupled to the first operational transconductance amplifier;

detecting, by a sensing system coupled to the first driver circuit, a touch based on a change in capacitance at the electrode of the plurality of electrodes of the touch sensor;

providing, by the first current mirror, a first current to the sensing system;

providing, by a second current mirror coupled to the sensing system, a second current to the sensing system;

providing to the sensing system, by a third current mirror coupled to the first current mirror and to the sensing system, a third current that is opposite in polarity to the first current; and

providing to the sensing system, by a fourth current mirror coupled to the second current mirror and to the sensing system, a fourth current that is opposite in polarity to the second current.

6. The method of claim 5 , wherein:

a second driver circuit is coupled to a second electrode of the plurality of electrodes; and

the first current mirror and the second current mirror are coupled to the second driver circuit.

7. A method comprising:

driving, by a first operational transconductance amplifier of a first driver circuit, a current through a first current mirror to an electrode of a plurality of electrodes of a touch sensor; and

detecting, by a sensing system coupled to the first driver circuit, a touch based on a change in capacitance at the electrode of the plurality of electrodes of the touch sensor, wherein:

a second current mirror is coupled to the sensing system;

a first switch is coupled to the first current mirror;

a second switch is coupled to the first current mirror and to the first operational transconductance amplifier;

a third switch is coupled to the first operational transconductance amplifier and to the second current mirror;

a fourth switch is coupled to the second current mirror;

a fifth switch is coupled to the first operational transconductance amplifier;

a sixth switch is coupled to the first operational transconductance amplifier; and

a seventh switch is coupled to the first operational transconductance amplifier, the first current mirror, and the second current mirror.

8. The method of claim 7 , further comprising:

closing the second switch, the fourth switch, and the seventh switch when a rate of change of an input voltage to the first driver circuit is positive; and

opening the first switch, the third switch, the fifth switch, and the sixth switch when the rate of change of the input voltage to the first driver circuit is positive.

9. The method of claim 7 , wherein:

the first switch and the fourth switch are closed when a rate of change of an input voltage to the first driver circuit is zero; and

the second switch, the third switch, and the seventh switch are open when the rate of change of the input voltage to the first driver circuit is zero.

10. The method of claim 7 , further comprising:

closing the first switch, the third switch, and the seventh switch when a rate of change of an input voltage to the first driver circuit is negative; and

opening the second switch, the fourth switch, the fifth switch, and the sixth switch when the rate of change of the input voltage to the first driver circuit is negative.

Assignments (10)

Continuity (2)