METHOD AND APPARATUS FOR BLOCKING ACCUMULATION OF ELECTRICAL FAST TRANSIENT (EFT) NOISE

摘要

A charge sensing circuit generates a voltage in a sensing period that is indicative of sensed charge. The generated voltages are accumulated by an accumulator circuit over a number of sensing periods. A noise detection circuit senses when the voltage generated by the charge sensing circuit is outside of a boundary and generates a detection signal in response thereto. A control circuit, in response to the detection signal, controls the accumulator circuit to block accumulation of the voltages generated by the charge sensing circuit during at least the sensing period in which the detection signal is generated. An analog-to-digital converter circuit then converts an accumulated output voltage from the accumulator circuit to a digital value at the end of an accumulation time period that includes the sensing periods. The end of the accumulation time period is delayed by at least one sensing period in response to the detection signal.

主权项

1. A circuit, comprising:
a charge sensing circuit configured to generate a voltage in a sensing period that is indicative of sensed charge; an accumulator circuit configured to accumulate the voltages over a plurality of said sensing periods; a noise detection circuit configured to sense when the voltage generated by the charge sensing circuit is outside of a boundary and generate a noise event detection signal in response thereto; and a control circuit configured to receive the noise event detection signal and control the accumulator circuit to block accumulation of the voltage generated by the charge sensing circuit during at least the sensing period in which the noise event detection signal is generated.