Circuit for Heartbeat Detection and Beat Timing Extraction

A method for detecting a heartbeat comprising the steps of:

• amplifying a signal from an ECG electrode to form an amplified ECG signal;
• amplifying the amplified ECG signal with an amplifier having a bandwidth of 20-40 Hz to form a QRS signal;
• amplifying the amplified ECG signal with an amplifier having a bandwidth of 1 Hz to generate baseline voltage;
• adding a DC offset to the baseline to form an offset baseline;
• comparing the QRS signal to the offset baseline;
• and
• generating an output signal if the QRS signal is greater than the offset baseline.

A method of selecting a DC offset comprising the steps of:

• a. setting a DC voltage to a predetermined value;
• b. comparing an amplified filtered ECG signal to the sum of a baseline signal and the DC voltage to produce an output signal;
• c. if the output signal is not a series of regularly spaced pulses of 40 ppm to 180 ppm then incrementing the DC voltage;
• d. iteratively repeating steps b and c until the output signal is a series of regularly spaced pulses of 40 ppm to 180 ppm;
• and
• e. setting the DC offset at the value of the DC voltage.

A method of selecting an offset baseline comprising the steps of:

• a. determining the peak voltage of an R-wave of a heartbeat;
• b. determining a baseline DC voltage;
• and
• c. calculating one half the difference between the baseline DC voltage and peak voltage of the heartbeat and adding the baseline DC voltage to obtain the offset baseline.

A detection device comprising:

• an amplifier cell having a plurality of input terminals and an output terminal;
• a signal amplifier cell having an input terminal and an output terminal, the input terminal of the signal amplifier cell in communication with the output terminal of the amplifier cell;
• a baseline amplifier cell having an input terminal and an output terminal, the input terminal of the baseline amplifier cell in communication with the output terminal of the amplifier cell;
• a comparator cell having a first input terminal and a second input terminal and an output terminal, the first input terminal of the comparator cell in communication with the output terminal of the signal amplifier cell;
• and
• a VDC cell having a first terminal in communication with the output terminal of the baseline amplifier cell and a second terminal in communication with the second input terminal of the comparator cell,
• wherein the amplifier cell outputs an output signal on the output terminal of the amplifier cell in response to input signals input to the input terminals of the amplifier module,
• wherein the comparator cell generates an output pulse in response to the output signal from the signal amplifier cell and the output signal from the VDC cell.

A method for detecting a periodic signal comprising the steps of:

• amplifying a signal from a signal source to form an amplified signal;
• amplifying the amplified signal with an amplifier having a bandwidth sufficient to form a filtered amplified signal with highest frequency pulsatile features of amplified signal preserved;
• amplifying the amplified signal with an amplifier having a bandwidth sufficient to preserve the baseline while removing the pulsatile components;
• adding a DC offset to the baseline to form an offset baseline;
• comparing the filtered amplified signal to the offset baseline;
• and
• generating an output signal if the filtered amplified signal is greater than the offset baseline.