AC-coupled electrocardiogram signal acquisition system with enhanced common mode rejection

A system, comprising:

• a first amplifier having a non-inverting input, an inverting input and an output;
• a first capacitor coupled to the non-inverting input of the first amplifier;
• a second capacitor coupled the inverting input of the first amplifier;
• a first resistor having a first terminal and a second terminal wherein the first terminal is coupled to the non-inverting input of the first amplifier;
• a second resistor having a first terminal and a second terminal wherein the first terminal of the second resistor is coupled to the second terminal of the first resistor, and the second terminal of the second resistor is coupled to the inverting input of the first amplifier;
• an average estimation circuit having a first input coupled to the non-inverting input of the first amplifier, a second input coupled to the inverting input of the first amplifier, and an output wherein the output is an average a voltage at the non-inverting input and a voltage at the inverting input;
• a driver amplifier having an inverting input coupled to the output of the average voltage estimation circuit, a non-inverting input, and an output;
• a low-pass filter coupled to the output of the driver amplifier and resistor;
• and
• a third capacitor coupled between the output of the driver amplifier.

An electrocardiogram (ECG) signal acquisition system, comprising:

• a first amplifier having a non-inverting, an inverting input, and an output;
• a first resistor having a first terminal and a second terminal wherein the first terminal is coupled to the non-inverting input of hte first amplifier;
• a second resistor having a first terminal and a second terminal wherein the first terminal of the second resistor is coupled to the second terminal of the first resistor, and the second terminal of the second resistor is coupled to the inverting input of the first amplifier;
• an average estimation circuit having a first input coupled to the non-inverting input of the first amplifier and a second input coupled to the inverting input of the first amplifier, and an output;
• a driver amplifier having an inverting input coupled to the output of the average estimation circuit, a non-inverting input coupled to receive a first voltage, and an output;
• a low-pass filter having a third resistor coupled between the output of the driver amplifier and the second terminal of the first resistor and having a capacitor coupled to the second terminal of the first resistor and ground;
• and
• a load capacitor coupled between the output of the driver amplifier and a ground terminal.