Method and apparatus that models neural transmission to amplify a capacitively-coupled input signal

An apparatus for amplifying an input signal received from a capacitive sensor, comprising:

• an input that receives an input signal from the capacitive sensor;
• an amplifier that amplifies the input signal to produce an output signal;
• a pull-up circuit within the amplifier that pulls the output signal up to a high voltage when the input signal exceeds a threshold voltage;
• a pull-down circuit within the amplifier that pulls the output signal down to a low voltage when the input signal falls below the threshold voltage;
• an output that makes output signal available to other circuitry;
• a bi-stable circuit that is configured to hold the output to the high voltage until the input signal falls below the threshold voltage, and is configured to hold the output to the low voltage until the input signal rises above the threshold voltage;
• wherein after the output signal is pulled up to the high voltage, the pull-up circuit enters a refractory state in which the pull-up circuit uses a limited current, and the pull-down circuit enters a receptive state in which the pull-down circuit is sensitized to react to small changes in the input signal;
• wherein when the pull-down circuit is in the receptive state and the input voltage drops below the threshold voltage, the pull-down circuit is configured to enter an active state in which the pull-down circuit draws sufficient current to rapidly switch the output signal to the low voltage;
• wherein after the output signal is pulled down to the low voltage, the pull-down circuit enters a refractory state in which the pull-down circuit uses a limited current, and the pull-up circuit enters a receptive state in which the pull-up circuit is sensitized to react to small changes in the input signal;
• wherein when the pull-up circuit is in the receptive state and the input voltage rises above the threshold voltage, the pull-up circuit is configured to enter an active state in which the pull-up circuit draws sufficient current to rapidly switch the output signal to the high voltage.

A semiconductor chip that amplifies an input signal received from a capacitive sensor, comprising:

• the capacitive sensor in the form of an I/O pad on a surface of the semiconductor chip that receives an input signal;
• an amplifier that amplifies the input signal to produce an output signal;
• a pull-up circuit within the amplifier that pulls the output signal up to a high voltage when the input signal exceeds a threshold voltage;
• a pull-down circuit within the amplifier that pulls the output signal down to a low voltage when the input signal falls below the threshold voltage;
• wherein after the output signal is pulled up to the high voltage, the pull-up circuit enters a refractory state in which the pull-up circuit uses a limited current, and the pull-down circuit enters a receptive state in which the pull-down circuit is sensitized to react to small changes in the input signal;
• wherein after the output signal is pulled down to the low voltage, the pull-down circuit enters a refractory state in which the pull-down circuit uses a limited current, and the pull-up circuit enters a receptive state in which the pull-up circuit is sensitized to react to small changes in the input signal;
• and
• an output that makes output signal available to other circuitry on the semiconductor chip.

A method for amplifying an input signal received from a capacitive sensor, comprising:

• receiving an input signal from the capacitive sensor;
• and
• amplifying the input signal to produce an output signal;
• wherein when the input signal exceeds a threshold voltage, amplifying the input signal involves,
• using a pull-up circuit to pull the output signal up to a high voltage,
• causing the pull-up circuit to enter a refractory state in which the pull-up circuit uses a limited current, and
• causing a pull-down circuit enters a receptive state in which the pull-down circuit is sensitized to react to small changes in the input signal;
• wherein when the input signal falls below the threshold voltage, amplifying the input signal involves,
• using the pull-down circuit to pull the output signal down to a low voltage,
• causing the pull-down circuit enters a refractory state in which the pull-down circuit uses a limited current, and
• causing the pull-up circuit to enter a receptive state in which the pull-up circuit is sensitized to react to small changes in the input signal.