High input impedance biomedical front-end detection circuit and related method

Abstract

The invention discloses a biomedical front-end detection circuit with high input impedance. The input impedance of the biomedical front-end detection circuit is improved by an automatic improvement circuit on an input impedance sheet. The front-end detection circuit specifically comprises a reconfigurable instrument amplifier, an adjustable gain amplifier and an input impedance on-chip automatic improving circuit. The reconfigurable instrument amplifier and the adjustable gain amplifier are used for amplifying biological signals at different gain multiplying powers; the automatic increasing circuit on the input impedance chip increases the input impedance of the amplifying circuit and ensures the stability of the circuit at the same time by automatically adjusting a positive feedback capacitor connected into the reconfigurable instrument amplifier. The high input impedance of the circuit improves the anti-interference capability of the circuit, reduces the attenuation of a biological signal on a detection electrode in practical application, and can realize high-quality detection of the biological signal.

Description

technical field [0001] The invention belongs to integrated circuits, and in particular relates to a biomedical front-end detection circuit with high input impedance and related methods. Background technique [0002] High input impedance amplifier circuits are widely used in the field of biomedical front-end sampling. The amplitude of the biological signal is weak (between hundreds of microvolts (uV) and several millivolts (mV)), and most of the biological signals are coupled into the amplification circuit through electrodes. Common electrodes are divided into wet electrodes, dry electrodes and non-contact electrodes. Among them, the dry electrode and the non-contact electrode have better comfort and stability, but due to the high impedance (>MΩ) of these two electrodes, the equivalent internal resistance of the biological signal coupled into the amplifier circuit is relatively large, so Amplifying circuits with high input impedance are required for high-quality acquisiti...

AI Technical Summary

Problems solved by technology

The three-op-amp structure has high power consumption and is not suitable for long-term biological signal detection; the pre-charge structure cannot achieve a good input impedance improvement effect due to the charging time and buffer non-ideality; and the last structure requires off-chip Manual intervention increases test time and cost

However, the positive feedback capacitor array of this method is always connected to the circuit in the form of positive feedback during the calibration period. The closer the positive feedback capacitor array is to the calibration ideal value, the longer it takes for the entire system to reach a stable output. Detecting the output value will cause the next calibration cycle to be entered before a stable output is observed within the calibration signal detection cycle.

The input impedance improvement accuracy of this method is affected by the calibration signal detection cycle, it is a qualitative calibration rather than a quantitative calibration, and it is difficult to accurately find the calibration boundary

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