Abstract: This invention discloses a non-invasive electroencephalography (BEG) signal recorder and a multiband active electrode (MAE) EEG cap array. A narrow-band amplification method is disclosed that divides the desired bandwidth of the input brain signal to smaller bands, each recorded using a separate amplification path. A novel twisted differential feedback topology is disclosed for both amplifiers and active filters having ultra-high input impedance. A one-wire EEG cap array of tightly connected MAEs is disclosed that improves the flexibility and portability of the EEG cap by reducing the number of wires between the EEG cap and the host processor. Due to having MAEs embedded inside electrodes, the output signals of electrodes are digital information. The tightly connected network of MAEs enables the reference electrode to be chosen dynamically. Moreover, the voltage of the reference node is adjusted using a correction feedback loop before each recording step.