A Novel Current-Mode EMG Interface

This paper presents the design of a current-mode read-out circuit for EMG monitoring employing second-generation current conveyors (CCIIs) and second-generation voltage conveyors (VCII) as active blocks. After a quick overview of the current-mode approach, the paper describes the whole interface, composed by three active blocks, and its operation. The proposed circuit was simulated by LTspice simulator firstly designing the internal blocks at transistor level, in 0.18 μm standard CMOS technology, and then using the commercially available device AD844 to demonstrate the validity of the designed circuit also with simulations. The voltage gain is tunable by changing some resistance values in the different stages of the amplifier. In the proposed solution, CMRR has been set to be more than 100 dB, being the common mode gain about-40 dB. The aim of this research is to test the performance of biological signal amplifiers using the current-mode approach (in particular, VCII) which is still underutilized in this context. The goal is to provide a more efficient and versatile system for biomedical applications.