Pre-stage circuit in bioelectricity detection

The invention discloses a pre-stage circuit in bioelectricity detection. The pre-stage circuit in bioelectricity detection comprises a fundamental circuit module (1) combined with a high-pass filter and an instrumentation amplifier, a closed feedback circuit module (2) restraining common-mode interference and the like. The pre-stage circuit in bioelectricity detection is characterized in that the fundamental circuit module (1) is connected with a capacitor C on the portion of a variable gain resistor RG of the instrumentation amplifier in series, the output vo integral of the instrumentation amplifier is fed back to an original grounded reference end vf of an instrument operational amplifier by the fundamental circuit module (1), and the original grounded reference end vf of the instrument operational amplifier is no longer grounded. According to the scheme, high gain of the pre-stage circuit is guaranteed and the damping capacity of an attenuation band of the pre-stage circuit is further improved.