Current-reuse low power instrumentation amplifier and fully differential differential amplifiers included therein

摘要

The present invention relates to a current reuse instrumentation amplifier. The low-power measuring amplifier according to an embodiment of the present invention includes an electrode unit including a first electrode and a second electrode for detecting an electrocardiogram signal; A fully differential differential amplifier to which the first and second electrodes and a non-inverting input terminal (+ terminal) are connected; An AC coupling feedback circuit that receives the output of the fully differential amplifier and feeds it back to the inverting input terminal (-terminal) of the fully differential amplifier through a feedback structure, wherein the AC coupling feedback circuit includes a variable capacitor and a pseudo resistor ( An AC coupling feedback circuit, including a pseudo resistor); And a resistance regulator that adjusts the magnitude of the pseudo resistance included in the AC coupling feedback circuit. The current reuse instrumentation amplifier has a high input impedance by using a current feedback instrumentation amplifier (CFIA) structure, and a high power rejection ratio (PSRR, Power) by adopting a Fully Differential Difference Amplifier (FDDA). Supply Rejection Ratio) and Common Mode Rejection Ratio (CMRR) can be secured. In addition, an AC-coupled capacitive feedback structure can be used to remove unnecessary low frequency components.