Input/output capacitance reduction with negative impedance

A method comprising:

• receiving an input signal from a signal conductor pad;
• and
• generating a capacitance-cancelled signal at a capacitance cancelling circuit based on the input signal, the capacitance cancelling circuit including:
• a pad capacitor conductively coupled to the signal conductor pad;
• and
• a negative impedance circuit including:
• an operational amplifier with a non-inverting opamp input conductively coupled to receive the input signal from the pad capacitor;
• a direct current blocking capacitor conductively coupled between the non-inverting opamp input and an opamp output;
• a first resistor conductively coupled between an inverting opamp input and a ground;
• and
• a second resistor conductively coupled between the inverting opamp input and the opamp output.

A circuit comprising:

• a signal conductor pad to receive an input signal;
• a capacitance cancelling circuit to generate a capacitance-cancelled signal based on an input signal received from the signal conductor pad, wherein the capacitance cancelling circuit includes:
• a pad capacitor conductively coupled to the signal conductor pad to receive the input signal;
• and
• a negative impedance circuit including:
• an operational amplifier including a non-inverting opamp input conductively coupled to receive the input signal from the pad capacitor, an inverting opamp input, and an opamp output;
• a direct current blocking capacitor conductively coupled between the non-inverting opamp input and the opamp output;
• an impedance-setting network conductively coupled to the inverting opamp input to define a negative impedance characteristic of the negative impedance circuit;
• and
• a comparator circuit to generate an equalized output based on the capacitance-cancelled signal.