Biological data differential amplifier - differentiates signal to ease analysis of continually changing data representing e.g. breathing, blood pressure

摘要

A differential amplifier calculates the rate of change of measured biological data e.g. breathing, blood pressure. The input to the amplifier is an electrical signal proportional to the size of the data. The signal is differentiated and then compared with a triangular or trapezoidal signal with one of the flat portions following a curve. The amplifier has a variable amplification factor and contains two stages to give the differential and the second differential of the signal. The time constant dt can be changed. A rectifier circuit is included to by-pass the differential circuits and remove the rise or fall portion of the signal. An envelope demodulator circuit is between the rectifier circuit and the output.