I have tried to design an surface Electromyograph front end sensor, using the TI INA118P instrumentation amplifier IC with a stage 1 gain of 20...followed by two filters ( a high pass filter of 10Hz cut off and a low pass filter of 300 Hz) to band-limit the signal between 10-300Hz...(active 1st order filters using IC TLC 272). Also, i'd put in an elbow drive circuit. But I have noticed that a bias voltage of around 1V,200mHz had to be applied, to get the output..else the circuit wouldn't work....is there any way i can eliminate the need for this bias input...??