Physiological signal acquisition system and method with improved noise and common mode rejection performance and signal quality

A system for measuring a physiological brain signal with deep brain electrodes comprising

• at least two deep brain electrodes for measuring the physiological brain signal, a circuitry for acquisition of the physiological brain signal from the two deep brain electrodes with analog front-end circuitry, and an output for displaying for the physiological brain signal
• the circuitry for acquisition of the physiological signal with analog front-end circuitry comprising:
• at least two bootstrapped filters each comprising a resistor, a first capacitor and a second capacitor, and a unity gain buffer, the resistor and first capacitor of each bootstrapped filter forming a low-pass filter and the second capacitor is driven to have substantially the same upper and lower alternating current (AC) voltage as when the EEG physiological signal is input into the system, the second capacitor being driven by a common mode signal or a physiological signal potential;
• and
• at least one instrumentation amplifier, each instrumentation amplifier comprising at least two amplifiers;
• wherein the bootstrapped filters are each directly connected to a common node for each of the at least two amplifiers for each of the at least two instrumentation amplifiers, the bootstrapped filters external to each of the instrumentation amplifiers and adapted to remove common mode signal from the physiological brain signal prior to the signal entering the instrumentation amplifier, and the system is adapted to allow additional channels to be added by adding an additional bootstrapped filter and using an existing channel as a reference and the system is adapted to have a common mode rejection ratio of 95 or greater dB.

A physiological signal acquisition system comprising:

• (a) at least two physiological sensors configured to acquire differential biopotential signals from a subject;
• (b) analog front-end circuitry including dynamically controlled bootstrapped impedance networks electrically interposed between the physiological sensors and an instrumentation amplifier;
• (c) an instrumentation amplifier comprising at least two internal amplifier stages;
• and
• (d) a processor configured to compute at least one physiological metric from an output of the instrumentation amplifier;
• wherein the bootstrapped impedance networks are dynamically driven by feedback derived from a node downstream of an input stage of the instrumentation amplifier to compensate for time-varying sensor-to-subject impedance during active signal acquisition.