Ground noise suppression on a printed circuit board

An apparatus comprising:

• a first amplifier having first and second amplifier inputs and a first amplifier output;
• wherein the first amplifier input is coupled to a first ground reference terminal;
• wherein the second amplifier input is coupled to a power supply terminal through a first variable capacitor, and coupled to a second ground reference terminal through a second variable capacitor;
• and
• a second amplifier having third and fourth amplifier inputs and a second amplifier output, wherein the first amplifier output is coupled to the third amplifier input;
• and
• wherein the first amplifier output is opposite in polarity and has approximately equal amplitude to the sum of the noise capacitively coupled to the second amplifier from the second ground reference terminal and the noise capacitively coupled to the second amplifier from the power supply terminal.

A method for reducing noise comprising:

• coupling a first ground reference terminal to a first input of a first amplifier;
• coupling a power supply terminal to a second input of the first amplifier through a first variable capacitor;
• coupling a second ground reference terminal to the second input of the first amplifier through a second variable capacitor;
• adjusting the capacitance values of the first variable capacitor and the second variable capacitor to reduce noise at an adjustment terminal;
• and
• coupling an output of the first amplifier to an input of a second amplifier through a capacitor.