Full-differential same-phase parallel amplifying device for acquiring bioelectric signal

Abstract

The invention discloses a full-differential same-phase parallel amplifying device for acquiring a bioelectric signal. The amplifying device comprises an input buffer circuit, a differential filtering circuit, a data selector, a same-phase parallel amplifying circuit and an analog-digital conversion circuit which are connected sequentially. The input buffer circuit performs impedance conversion on the bioelectric signal first; the bioelectric signal subjected to low-pass filtering by the differential filtering circuit passes through the data selector and the same-phase parallel amplifying circuit; the bioelectric signal is amplified and a common-mode signal is suppressed; the noise of the bioelectric signal outside a signal high-frequency band is filtered through an anti-aliasing filtering network; and the amplified signal is subjected to analog-digital conversion by the analog-digital conversion circuit and then is output. The noise and common-mode suppression ratio can reach a high index, a base line is stable, a dynamic signal input range is wide, signals are difficult to saturate, and the device has high in reliability and can support perfect PACE detection. Meanwhile, the circuits are simple and are low in cost, and the device can be used for various bioelectric detection instruments and systems and has obvious economic benefit.

Description

technical field [0001] The invention relates to a device for collecting bioelectrical signals, in particular to a bioelectrical signal collecting device with full differential in-phase parallel amplification. Background technique [0002] As we all know, bioelectrical signal detection is carried out in the presence of strong background interference and the presence of patient polarization voltage. Due to the influence of strong interference (especially power frequency interference), instrumentation amplifiers are required. Bioelectrical signals are very weak and often need to be amplified by hundreds of times. When the electrode is in contact with the human skin, there is a polarization voltage, so the first-stage gain of the general amplifier is relatively small. It is necessary to isolate the polarization voltage with a resistance-capacitance circuit and then use the second-stage amplifier for amplification. Due to the existence of the time constant circuit, the capacitor...

AI Technical Summary

Problems solved by technology

Due to the presence of a time constant circuit, the capacitor will be charged when the patient’s polarization voltage is relatively large and the output of the first stage is saturated. Assuming that the patient’s condition is stable at this time (the patient’s upper polarization voltage reaches a relatively small normal value), then It takes a very long time for the charge on the DC blocking capacitor to be released, and ECG signal acquisition cannot be performed during this period

Therefore, the signal output speed of the AC device is slow, and the baseline is easy to drift, and the baseline recovery is slow

The traditional AC amplification has the following disadvantages: the signal dynamic range is small; the circuit is very complex and noisy; the amplifier saturation and baseline recovery are slow (baseline drift) problems

[0004] The circuit is still relatively complex, and there are many amplification links, which is not good for the noise of the control system; the ability to suppress common-mode interference is poor

At the same time, the signals after the instrumentation amplifier are all single-ended signals, and the common-mode interference on the signal line after the space coupling to the instrumentation amplifier cannot be ruled out.

[0005] The cost is high, and the instrument amplifier is generally expensive. If the instrument amplifier is built with three op amps, on the one hand, the cost is still higher than the in-phase parallel amplifier structure in this paper. On the other hand, the instrument amplifier built with three op amps has a limited common-mode rejection ratio. Due to the accuracy of matching resistors, it is difficult to improve, generally 60dB is quite good

[0006] In short, it is difficult to avoid the problems of high cost and unsatisfactory common-mode rejection ratio at the same time by using traditional DC amplifier circuit devices

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