Inverting current amplification and related touch systems
AssigneeMicrochip Technology Incorporated
InventorLei Zou
Life of this patent
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Abstract
One or more examples relate to inverting current amplification and related touch systems. An apparatus includes a first transistor, a second transistor, and a feedback loop. The first transistor and the second transistor provide controlled current at the second transistor that is a copy of current at the first transistor when respective drain-source voltages of the first transistor and the second transistor are substantially equal. The feedback loop sets respective drain-source voltages of the first transistor and the second transistor to be substantially equal, wherein a responsiveness of the feedback loop is proportional to a set transconductance of the feedback loop.
Claims28
An apparatus, comprising:
- a first transistor and a second transistor to provide a controlled current at the second transistor that is a copy of current at the first transistor when respective drain-source voltages of the first transistor and the second transistor are substantially equal;
- and
- a feedback loop to set the respective drain-source voltages of the first transistor and the second transistor to be substantially equal, wherein a responsiveness of the feedback loop is proportional to a set transconductance of an operational transconductance amplifier (OTA) of the feedback loop.
An apparatus, comprising:
- a first current amplification circuit to receive an input current from a first touch electrode;
- and
- a second current amplification circuit to receive an input current from a second touch electrode,
- wherein the first current amplification circuit comprises:
- a current amplifier to amplify the input current received from the first touch electrode;
- an inverting current amplifier to invert the amplified input current with gain≥(−0.99);
- and
- a summer to combine the amplified input current and an inverted amplified input current generated at the second current amplification circuit.
A method, comprising:
- receiving a measurement charge signal from a first electrode and a measurement charge signal from a second electrode, both in response to a capacitive measurement process;
- generating inverted versions of the measurement charge signal received from the first electrode and the measurement charge signal from the second electrode;
- obtaining a touch charge signal for the second electrode by combining the inverted version of the measurement charge signal from the first electrode with the measurement charge signal from the second electrode;
- and
- detecting a state of the first electrode at least partially responsive to touch charge signal for the first electrode.
A method, comprising:
- setting respective drain voltages of a first transistor and a second transistor to be substantially equal utilizing an operational transconductance amplifier (OTA) having a set bandwidth;
- and
- providing a controlled current at the second transistor that is a copy of a current at the first transistor when respective drain-source voltages of the first transistor and the second transistor are substantially equal.
Dependencies are inferred from the claim text.